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EN 50122-1:2011: Railway applications Fixed installations - Electrical safety,
earthing and the return circuit -- Part 1:
Protective provisions against electric
shock [Required by Directive 2008/57/EC]
Юни 2011
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БДС EN 50122-1
Заменя:
БДС EN 50122-1:2004.
ICS: 29.280
Железопътна техника. Стационарни инсталации. Електрическа
безопасност, заземяване и обратна верига. Част 1: Предписания
за защита срещу поражение от електрически ток
Railway applications - Fixed installations - Electrical safety, earthing and the return circuit
-- Part 1: Protective provisions against electric shock
Европейският стандарт EN 50122-1:2011 има статут на български стандарт от
2011-06-17.
Този стандарт е официалното издание на Българския институт за стандартизация на
английски език на европейския стандарт EN 50122-1:2011.
83 стр.
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НАЦИОНАЛЕН ПРЕДГОВОР
Този стандарт е подготвен с участието на БИС/TK 70 "Железопътен транспорт".
Следват 81 страници на EN 50122-1:2011.
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7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
EUROPEAN STANDARD
EN 50122-1
NORME EUROPÉENNE
January 2011
EUROPÄISCHE NORM
ICS 29.280
Supersedes EN 50122-1:1997
English version
Railway applications Fixed installations Electrical safety, earthing and the return circuit Part 1: Protective provisions against electric shock
Applications ferroviaires Installations fixes Sécurité électrique, mise à la terre et
circuit de retour Partie 1: Mesures de protection contre les
chocs électriques
Bahnanwendungen Ortsfeste Anlagen Elektrische Sicherheit, Erdung und
Rückleitung Teil 1: Schutzmaßnahmen gegen
elektrischen Schlag
This European Standard was approved by CENELEC on 2010-11-16. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Management Centre: Avenue Marnix 17, B - 1000 Brussels
© 2011 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50122-1:2011 E
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EN 50122-1:2011
–2–
Foreword
This European Standard was prepared by SC 9XC, Electric supply and earthing systems for public transport
equipment and ancillary apparatus (Fixed installations), of Technical Committee CENELEC TC 9X, Electrical
and electronic applications for railways. It was submitted to the formal vote and was approved by CENELEC
as EN 50122-1 on 2010-11-16.
This document supersedes EN 50122-1:1997.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent rights.
The following dates were fixed:
–
–
latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement
(dop)
2011-11-16
latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2013-11-16
This European Standard has been prepared under a mandate given to CENELEC by the European
Commission and the European Free Trade Association and covers essential requirements of
EC Directives 96/48/EC (HSR), 2001/16/EC (CONRAIL) and 2008/57/EC (RAIL). See Annex ZZ.
__________
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–3–
EN 50122-1:2011
Contents
1!
Scope ....................................................................................................................................................... 7!
2!
Normative references ............................................................................................................................. 7!
3!
Terms and definitions ............................................................................................................................ 8!
4!
5!
6!
7!
8!
3.1!
Electrical safety and hazards ......................................................................................................... 8!
3.2!
Earthing and equipotential bonding .............................................................................................10!
3.3!
Return circuit ................................................................................................................................11!
3.4!
Electric traction system ................................................................................................................13!
3.5!
Contact line ..................................................................................................................................14!
3.6!
Corrosion and corrosion protection ..............................................................................................16!
3.7!
Current collection .........................................................................................................................16!
3.8!
Residual current devices ..............................................................................................................16!
3.9!
General terms...............................................................................................................................17!
Contact line zone and current collector zone ...................................................................................17!
4.1
Overhead contact line systems ....................................................................................................17
4.2
Conductor rail systems.................................................................................................................20
4.3
Trolleybus systems ......................................................................................................................20
Protective provisions against direct contact ....................................................................................22!
5.1
General .........................................................................................................................................22
5.2
Protection by clearance ................................................................................................................22
5.3
Protection by obstacles ................................................................................................................25
5.4
Protective provisions for working under live conditions ...............................................................33
5.5
Specific protective provisions against electric shock in conductor rail systems .......................... 36
5.6
Specific protective provisions against electric shock in systems in which the wheels of
the vehicles are not used for return circuit ...................................................................................40
Protective provisions against indirect contact and impermissible rail potential ..........................41!
6.1
Protective provisions against indirect contact ..............................................................................41
6.2
Protective provisions for exposed conductive parts within the contact line zone or the
current collector zone ...................................................................................................................42
6.3
Protective provisions for wholly or partly conductive structures ..................................................43
6.4
Limitation of rail potentials............................................................................................................45
Protective provisions for low voltage non traction power supplies ...............................................45!
7.1
General .........................................................................................................................................45
7.2
Related provisions ........................................................................................................................46
7.3
Protective provisions for electrical installations in the overhead contact line zone or the
current collector zone ...................................................................................................................46
7.4
Protective provisions for installations which are endangered by the traction power
supply return circuit ......................................................................................................................46
Protective provisions where track systems, which are utilized for carrying traction
return current, or/and contact line systems pass through hazardous zones ................................ 52!
8.1
General .........................................................................................................................................52
8.2
Equipotential bonding ...................................................................................................................53
8.3
Parallel pipework ..........................................................................................................................53
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EN 50122-1:2011
9!
10!
–4–
8.4
Insulating joints.............................................................................................................................53
8.5
Surge arrester ..............................................................................................................................54
8.6
Contact line of loading sidings .....................................................................................................54
Limits for touch voltage and protection against the danger of rail potential ................................54!
9.1
General .........................................................................................................................................54
9.2
A.C. traction systems ...................................................................................................................55
9.3
D.C. traction systems ...................................................................................................................59
Additional protective provisions ........................................................................................................61!
10.1 Traction substations and traction switching stations ....................................................................61
10.2 Cables ..........................................................................................................................................61
10.3 Return circuit connections and earthing conductors ....................................................................61
10.4 Removing of decommissioned overhead contact lines ................................................................62
10.5 Means of achieving safe isolation between sections ................................................................... 63
Annex A (informative) Typical obstacles .......................................................................................................64!
Annex B (normative) Warning sign ................................................................................................................66!
Annex C (informative) Guiding values for rail potential gradient ...............................................................67!
C.1
A.C. traction systems ...................................................................................................................67
C.2
D.C. traction systems ...................................................................................................................68
Annex D (informative) Effective touch voltage and body voltage with respect to the body
current ...................................................................................................................................................69!
D.1
Preconditions for the calculation ..................................................................................................69
D.2
Impedances ..................................................................................................................................69
D.3
Body current and related body voltage ........................................................................................72
Annex E (normative) Measurement methods for effective touch voltages................................................75!
Annex F (normative) The use of voltage-limiting devices ........................................................................... 76!
F.1
General .........................................................................................................................................76
F.2
Types ............................................................................................................................................76
F.3
Technical requirements ................................................................................................................76
Annex G (normative) Special national conditions ........................................................................................ 77
Annex H (normative) A-deviations .................................................................................................................80
Annex ZZ (informative) Coverage of Essential Requirements of EC Directives........................................ 80!
Bibliography ....................................................................................................................................................81!
Figures
Figure 1 — Overhead contact line zone and current collector zone ................................................................19!
Figure 2 — Overhead contact line zone and current collector zone for trolley bus systems ...........................21!
Figure 3 — Minimum clearances to accessible live parts on the outside of vehicles as well as to live
parts of overhead contact line systems from standing surfaces accessible to persons for low
voltages.............................................................................................................................................................23!
Figure 4 — Minimum clearances to accessible live parts on the outside of vehicles as well as to live
parts of overhead contact line systems from standing surfaces accessible to persons for high
voltages.............................................................................................................................................................23!
Figure 5 — Standing surfaces for persons providing access to live parts on the outside of vehicles
and to overhead contact line systems ..............................................................................................................25!
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–5–
EN 50122-1:2011
Figure 6 — Standing surfaces for persons providing access to live parts on the outside of vehicles
and to conductor rail systems ...........................................................................................................................26!
Figure 7 — Examples of obstacles for standing surfaces in public areas for protection against direct
contact with adjacent live parts on the outside of vehicles or adjacent live parts of a contact line
system...............................................................................................................................................................27!
Figure 8 — Examples of obstacles for standing surfaces in restricted areas for protection against
direct contact with adjacent live parts on the outside of vehicles or adjacent live parts of a contact
line system for low voltages ..............................................................................................................................30!
Figure 9 — Examples of obstacles for standing surfaces in restricted areas for protection against
direct contact with adjacent live parts on the outside of vehicles or adjacent live parts of a contact
line system for high voltages ............................................................................................................................31!
Figure 10 — Examples of obstacles for standing surfaces in restricted areas for protection against
direct contact when above live parts on the outside of vehicles or live parts of a contact line system
for low voltage ...................................................................................................................................................32!
Figure 11 — Examples of obstacles for standing surfaces in restricted areas for protection against
direct contact when above live parts on the outside of vehicles or live parts of an overhead contact
line system for high voltage ..............................................................................................................................33!
Figure 12 — Example of an insulated obstacle beneath a structure ................................................................34!
Figure 13 — Example of an insulated obstacle beneath a structure for an unearthed trolley bus
system...............................................................................................................................................................35!
Figure 14 — Example of an insulated obstacle beneath a structure for a trolley bus system in which
the negative contact wire is earthed or connected to the return circuit of a tramway system ..........................36!
Figure 15 — Public level crossing, private level crossing ................................................................................37!
Figure 16 — Trackside structures ....................................................................................................................38!
Figure 17 — Signal-post with telephone...........................................................................................................39!
Figure 18 — Authorized trackside walking route ..............................................................................................39!
Figure 19 — Railway controlled crossing (depots, goods yard, station crossing) ............................................40!
Figure 20 — TT system for a.c. railways ..........................................................................................................49!
Figure 21 — TN system for a.c. railways ..........................................................................................................50!
Figure 22 — TT system for d.c. railways ..........................................................................................................51!
Figure 23 — TN system for d.c. railways ..........................................................................................................52!
Figure 24 — Disposition of rail-to-rail cross bonds and track-to-track cross bonds (double-rail
illustration) and connection of the contact line in case of the loading siding having a contact line ..................53!
Figure 25 — Location of a surge arrester outside the overhead contact line zone of a loading siding
if there is a possibility of flashovers of the insulating pieces through lightning strikes .....................................54!
Figure 26 — Design of return circuit, with regard to permissible effective touch voltage by checking
the rail potential or the effective touch voltage .................................................................................................58!
Figure A.1 — Examples of obstacles along the sides of standing surfaces in public areas for
protection against direct contact when above live parts on the outside of vehicles or live parts of an
overhead contact line system for low voltages (see 5.3.2.2)............................................................................64!
Figure A.2 — Examples of obstacles along the sides of standing surfaces in public areas for
protection against direct contact when above live parts on the outside of vehicles or live parts of an
overhead contact line system for high voltages (see 5.3.2.2) ..........................................................................65!
Figure B.1 — Warning sign...............................................................................................................................66!
Figure C.1 — Guidance values for the rail potential gradient measured at the mast in a right angle
to the track in an a.c. traction system ...............................................................................................................67!
Figure D.1 — Equivalent circuit for the calculation of the permissible touch voltage .......................................71!
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EN 50122-1:2011
–6–
Tables
Table 1 — Maximum dimensions for small conductive parts ...........................................................................44!
Table 2 — Kinds of auxiliary supplies...............................................................................................................47!
Table 3 — Maximum permissible body voltages Ub, max in a.c. traction systems as a function of time
duration .............................................................................................................................................................56!
Table 4 — Maximum permissible effective touch voltages Ute, max in a.c. traction systems as a
function of time duration ...................................................................................................................................57!
Table 5 — Maximum permissible body voltages Ub, max in d.c. traction systems as a function of time
duration .............................................................................................................................................................59!
Table 6 — Maximum permissible effective touch voltages Ute, max in d.c. traction systems as a
function of time duration ...................................................................................................................................60!
Table C.1 – Guidance values for the rail potential gradient (see Figure C.1) .................................................. 68!
Table D.1 — Body impedance Zb and body current Ib .................................................................................... 70!
Table D.2 — Example of the maximum permissible prospective touch voltage for a.c. railways for
short-term conditions and Ra = 1 150 ! ............................................................................................................72!
Table D.3 — Body currents, body voltages and touch voltages as function of time duration in a.c.
traction systems ................................................................................................................................................73!
Table D.4 — Body currents, body voltages and touch voltages as function of time duration in d.c.
traction systems ................................................................................................................................................74
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–7–
1
EN 50122-1:2011
Scope
This European Standard specifies requirements for the protective provisions relating to electrical safety in
fixed installations associated with a.c. and/or d.c. traction systems and to any installations that can be
endangered by the traction power supply system.
It also applies to all aspects of fixed installations that are necessary to ensure electrical safety during
maintenance work within electric traction systems.
This European Standard applies to all new lines and to all major revisions to existing lines for the following
electric traction systems:
a)
railways;
b)
guided mass transport systems such as
c)
1)
tramways,
2)
elevated and underground railways,
3)
mountain railways,
4)
trolleybus systems, and
5)
magnetically levitated systems, which use a contact line system,
material transportation systems.
This European Standard does not apply to:
d)
mine traction systems in underground mines;
e)
cranes, transportable platforms and similar transportation equipment on rails, temporary structures (e.g.
exhibition structures) in so far as these are not supplied directly or via transformers from the contact line
system and are not endangered by the traction power supply system;
f)
suspended cable cars;
g)
funicular railways.
This European Standard does not specify working rules for maintenance.
2
Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 50119:2009, Railway applications – Fixed installations – Electric traction overhead contact lines
EN 50122-2, Railway applications – Fixed installations – Part 2: Protective provisions against the effects of
stray currents caused by d.c. traction systems
EN 50124-1:2001 + A1:2003 + A2:2005, Railway applications – Insulation coordination – Part 1: Basic
requirements – Clearances and creepage distances for all electrical and electronic equipment
EN 50153:2002, Railway applications – Rolling stock – Protective provisions relating to electrical hazards
EN 50163, Railway applications – Supply voltages of traction systems
EN 60529:1991 + A1:2000,
(IEC 60529:1989 + A1:1999)
Degrees
of
protection
provided
by
enclosures
(IP
code)
EN 60898-1:2003 + A11:2005, Electrical accessories – Circuit-breakers for overcurrent protection for
household and similar installations – Part 1: Circuit-breakers for a.c. operation (IEC 60898-1:2002, mod.)
EN 61140:2002 + A1:2006, Protection against electric shock – Common aspects for installation and
equipment (IEC 61140:2001 + A1:2004, mod.)
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EN 50122-1:2011
–8–
HD 60364-4-41:2007, Low-voltage electrical installations – Part 4-41: Protection for safety – Protection
against electric shock (IEC 60364-4-41:2005, mod.)
HD 637 S1:1999, Power installations exceeding 1 kV a.c.
IEC 60050-101, International Electrotechnical Vocabulary – Chapter 101: Mathematics
IEC 60050-111, International Electrotechnical Vocabulary – Chapter 111: Physics and chemistry
IEC 60050-191, International Electrotechnical Vocabulary – Chapter 191: Dependability and quality of
service
IEC 60050-195, International Electrotechnical Vocabulary – Chapter 195: Earthing and protection against
electric shock
IEC 60050-442, International Electrotechnical Vocabulary – Chapter 442: Electrical accessories
IEC 60050-811, International Electrotechnical Vocabulary – Chapter 811: Electric traction
IEC 60050-821, International Electrotechnical Vocabulary – Chapter 821: Signalling and security apparatus
for railways
IEC 60050-826, International Electrotechnical Vocabulary – Chapter 826: Electrical installations
IEC/TS 60479-1:2005, Effects of current on human beings and livestock – Part 1: General aspects
ISO 3864-1:2002, Graphical symbols – Safety colours and safety signs – Part 1: Design principles for safety
signs in workplaces and public areas
ISO 7010:2003 + A1:2006, Graphical symbols – Safety colours and safety signs – Safety signs used in
workplaces and public areas
3
Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
Electrical safety and hazards
3.1.1
electrical safety
freedom from unacceptable risk of harm caused by electrical systems
3.1.2
electric shock
pathophysiological effect resulting from an electric current passing through a human or animal body
[IEC 60050-826-12-01]
3.1.3
(effective) touch voltage (Ute)
voltage between conductive parts when touched simultaneously by a person or an animal
NOTE 1 The value of the effective touch voltage can be appreciably influenced by the impedance of the person or the animal in electric
contact with these conductive parts
[IEC 60050-195-05-11]
NOTE 2 The conductive path through the body is conventionally from hand to both feet (horizontal distance of 1 m) or from hand to
hand.
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–9–
EN 50122-1:2011
3.1.4
prospective touch voltage (Utp)
voltage between simultaneously accessible conductive parts when those conductive parts are not being
touched by a person or an animal
[IEC 60050-195-05-09]
3.1.5
body voltage (Ub)
product of the current through the body and the body impedance
3.1.6
standing surface
any point on a surface where persons may stand or walk about without great effort
3.1.7
protective boarding
non-conducting barrier to protect persons from coming into direct contact with the live conductor rail
3.1.8
(electrically) protective obstacle
part preventing unintentional direct contact, but not preventing direct contact by deliberate action
[IEC 60050-195-06-16]
3.1.9
(electrically) protective barrier
part providing protection against direct contact from any usual direction of access
[IEC 60050-195-06-15]
3.1.10
anti-trespassing guard
equipment provided to deter entry to a restricted area, structure or building by an unauthorized person
3.1.11
conductive part
part which can carry electric current
[IEC 60050-195-01-06]
3.1.12
exposed conductive part
conductive part of electrical equipment, which can be touched and which is not normally live, but which can
become live when basic insulation fails
NOTE A conductive part of electrical equipment which can only become live through contact with an exposed conductive part which has
become live is not considered to be an exposed conductive part itself.
[IEC 60050-442-01-21]
3.1.13
live part
conductor or conductive part intended to be energised in normal use. By convention this does not include the
running rails and parts connected to them
3.1.14
direct contact
electric contact of persons or animals with live parts
[IEC 60050-826-12-03]
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EN 50122-1:2011
– 10 –
3.1.15
indirect contact
electric contact of persons or animals with exposed conductive parts which have become live under fault
conditions
[IEC 60050-826-12-04]
3.1.16
neutral conductor
conductor electrically connected to the neutral point and capable of contributing to the distribution of electric
energy
[IEC 60050-826-14-07]
3.1.17
protective conductor (PE)
conductor, required by some measures for protection against electric shock, for electrically connecting any of
the following parts:
–
exposed conductive parts;
–
extraneous conductive parts;
–
main earthing terminal;
–
earth electrode;
–
earthed point of the source or artificial neutral
3.1.18
PEN conductor
conductor combining the functions of both a protective earthing conductor and a neutral conductor
[IEC 60050-826-13-25]
3.1.19
solid-wall design
any kind of construction made of concrete, steel or other material without any holes or gaps
3.1.20
voltage-limiting device (VLD)
protective device whose function is to prevent existence of an impermissible high touch voltage
3.2
Earthing and equipotential bonding
3.2.1
earth
conductive mass of the earth, whose electric potential at any point is conventionally taken as equal to zero
[IEC 60050-826-04-01]
3.2.2
earthing
connection of conductive parts to an appropriate earth electrode
3.2.3
earth electrode
conductor or a group of conductors in intimate contact with and providing an electrical connection to earth
[IEC 60050-461-06-18]
3.2.4
structure earth
construction made of metallic parts or construction including interconnected metallic structural parts, which
can be used as an earth electrode
NOTE
Examples are reinforced railway structures such as bridges, viaducts, tunnels, mast foundations and reinforced track bed.
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
– 11 –
EN 50122-1:2011
3.2.5
rail to earth resistance
electrical resistance between the running rails and the earth or structure earth
3.2.6
equipotential bonding
provision of electric connections between conductive parts, intended to achieve equipotentiality
[IEC 60050-826-13-19]
3.2.7
main equipotential busbar (MEB)
busbar where the equipotential conductors terminate
3.2.8
cross bond
electrical connection intended to connect in parallel the conductors of the return circuit
3.2.9
rail-to-rail cross bond
electrical bond that interconnects the running rails of the same track
3.2.10
track-to-track cross bond
electrical bond that interconnects tracks
3.2.11
rail joint bond
conductor ensuring the electrical continuity of rails at a joint
[IEC 60050-811-35-07]
3.2.12
open connection
connection of conductive parts to the return circuit by a voltage-limiting device which makes a conductive
connection either temporarily or permanently if the limited value of the voltage is exceeded
3.2.13
common building
building or structure which contains or supports an a.c. railway and a d.c. railway; furthermore where some
conductive parts of the structure are within the contact line zone or the current collector zone of the a.c.
railway and some conductive parts of the structure are within the contact line zone or the current collector
zone of the d.c. railway
NOTE
Even the unintended connection of conductive parts of different structures can form a common building, e.g. via
reinforcement, wiring, pipes, etc.
3.3
Return circuit
3.3.1
return circuit
all conductors which form the intended path for the traction return current
EXAMPLE
The conductors may be:
–
running rails,
–
return conductor rails,
–
return conductors,
–
return cables.
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EN 50122-1:2011
– 12 –
3.3.2
track return system
system in which the running rails of the track form a part of the return circuit for the traction current
[IEC 60050-811-35-02]
3.3.3
return conductor
conductor paralleling the track return system and connected to the running rails at periodic intervals
3.3.4
return conductor rail – return current rail
conductor rail used instead of the running rail for the return currents
[IEC 60050-811-34-10]
3.3.5
return cable
conductor connecting the running rails or other parts of the return circuit to the substation
NOTE
Similar to IEC 60050-811-35-04.
3.3.6
traction return current
sum of the currents returning to the supply source, the substation or regenerative braking vehicles
3.3.7
rail potential (URE)
voltage occurring between running rails and earth
3.3.8
closed formation
area where the top of the running rails is at the same level as the surrounding surface
3.3.9
open formation
area where the running rails are laid above the surrounding surface
3.3.10
conductance per length G‘RE
reciprocal value of the rail to earth resistance per length (S/km)
3.3.11
insulating rail joint
mechanical rail joint which longitudinally separates the rail electrically
3.3.12
track circuit
electrical circuit of which the rails of a track section form a part, with usually a source of current connected at
one end and a detection device at the other end for detecting whether this track section is clear or occupied
by a vehicle
NOTE
In a continuous signalling system, the track circuit may be used to transmit information between the ground and the train.
[IEC 60050-821-03-01]
3.3.13
top of rail level (TOR)
common rail level tangent
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3.4
EN 50122-1:2011
Electric traction system
3.4.1
electric traction system
railway electrical distribution network used to provide energy for rolling stock
NOTE
The system may comprise:
–
contact line systems;
–
return circuit of electric traction systems;
–
running rails of non electric traction systems, which are in the vicinity of, and conductively connected to the running rails of an
electric traction system;
–
electrical installations, which are supplied from contact lines either directly or via a transformer;
–
electrical installations in substations, which are utilized solely for distribution of power directly to the contact line;
–
electrical installations of switching stations.
3.4.2
(traction) substation
installation to supply a contact line system and at which the voltage of a primary supply system, and in
certain cases the frequency, is transformed to the voltage and the frequency of the contact line
3.4.3
(traction) switching station
installation from which electrical energy can be distributed to different feeding sections or from which
different feeding sections can be switched on and off or can be interconnected
3.4.4
feeding section
electrical section of the route fed by individual track feeder circuit-breakers within the area supplied by the
substation
[EN 50119:2009, 3.3.2]
3.4.5
fault condition
non intended condition caused by short-circuit. The time duration is terminated by the correct function of the
protection devices and circuit breakers
NOTE
For the relevant fault duration the correct operation of protection devices and circuit breakers is taken into account.
3.4.6
short-circuit
accidental or intentional conductive path between two or more conductive parts forcing the electric potential
differences between these conductive parts to be equal to or close to zero
[IEC 60050-195-04-11]
3.4.7
high voltage
nominal voltage exceeding AC 1 000 V or DC 1 500 V
3.4.8
low voltage
nominal voltage up to and including AC 1 000 V or DC 1 500 V
3.4.9
zone of mutual interaction
zone for which a mutual interference between a.c. railway and d.c. railway shall be considered
3.4.10
expected prospective short-circuit current
short-circuit current in d.c. traction systems that it is expected to be reached if the fault is not switched off
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EN 50122-1:2011
3.5
– 14 –
Contact line
3.5.1
contact line system
support network for supplying electrical energy from substations to electrically powered traction units, which
covers overhead contact line systems and conductor rail systems; the electrical limits of the system are the
feeding point and the contact point to the current collector
NOTE The mechanical system may comprise:
!
the contact line,
!
structures and foundations,
!
supports and any components supporting or registering the conductors,
!
head and cross spans,
!
tensioning devices,
!
along-track feeders, reinforcing feeders, and other lines like earth wires and return conductors as far as they are supported from
contact line system structures,
!
any other equipment necessary for operating the contact line,
!
conductors connected permanently to the contact line for supply of other electrical equipment such as lights, signal operation,
!"
point control and point heating.
[EN 50119: 2009, 3.1.1]
3.5.2
contact line
conductor system for supplying traction units with electrical energy via current-collection equipment
NOTE This includes all current-collecting conductors and conducting rails or bars, including the following:
!
reinforcing feeders;
!
cross-track feeders;
!
disconnectors;
!
section insulators;
!
over-voltage protection devices;
!
supports that are not insulated from the conductors;
!
insulators connected to live parts;
but excluding other conductors, such as the following:
!
along-track feeders;
!
earth wires and return conductors.
[EN 50119:2009, 3.1.2]
3.5.3
overhead contact line system
contact line system using an overhead contact line to supply current for use by traction units
[EN 50119:2009, 3.1.3]
3.5.4
overhead contact line
contact line placed above (or beside) the upper limit of the vehicle gauge and supplying vehicles with electric
energy through roof-mounted current collection equipment
[IEC 60050-811-33-02]
3.5.5
out of running overhead contact line
part of overhead contact line, not intended to be directly used for current collection, e.g. in order to reach a
termination point on a mast or a structure
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EN 50122-1:2011
3.5.6
conductor rail system
contact line system using a conductor rail for current collection
[EN 50119:2009, 3.1.5]
3.5.7
conductor rail
contact line made of a rigid metallic section or rail, mounted on insulators located near the running rails
[EN 50119:2009, 3.1.7]
3.5.8
overhead conductor rail
rigid overhead contact line, of simple or composite section, mounted above or beside the upper limit of the
vehicle gauge, supplying traction units with electrical energy via roof-mounted current collection equipment
[EN 50119:2009, 3.1.6]
3.5.9
overhead contact line zone (OCLZ)
zone whose limits are in general not exceeded by a broken overhead contact line
3.5.10
current collector zone (CCZ)
zone whose limits are in general not exceeded by an energised collector no longer in contact with the
contact line or broken collector and its fragments
3.5.11
contact wire
electric conductor of an overhead contact line with which the current collectors make contact
[IEC 60050-811-33-15]
3.5.12
stagger
displacement of the contact wire away from the track centre line at successive supports, to avoid localised
wear of the pantograph wearing strips
[IEC 60050-811-33-21]
3.5.13
feeder
electrical conductor like a cable or overhead line between the contact line and a substation or a switching
station which is fed by a circuit breaker
3.5.14
reinforcing feeder
overhead conductor mounted adjacent to the overhead contact line, and directly connected to it at frequent
intervals, in order to increase the effective cross sectional area of the overhead contact line
[EN 50119:2009, 3.2.2]
3.5.15
section insulator
sectioning point formed by insulators inserted in a continuous run of a contact line, with skids or similar
devices to maintain continuous electrical contact with the collector
3.5.16
double insulation
insulation comprising both basic insulation and supplementary insulation
[IEC 60050-195-06-08]
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EN 50122-1:2011
3.6
– 16 –
Corrosion and corrosion protection
3.6.1
corrosion
electrochemical reaction of a metal with its environment, resulting in its progressive degradation or
destruction
NOTE
This European Standard deals with corrosion caused by stray currents.
3.6.2
leakage current
current which, in the absence of a fault, flows to earth or to extraneous conductive parts in a circuit
3.6.3
stray current (IS)
part of the current caused by a d.c.-traction system which follows paths other than the return circuit
3.6.4
cathodic protection
electrochemical immunity produced by an appropriate cathodic polarization
[IEC 60050-111-15-40]
3.7
Current collection
3.7.1
current collection
current transmission from contact line to a vehicle
3.7.2
current collector
equipment fitted to the vehicle and intended to collect current from a contact wire or conductor rail
[IEC 60050-811-32-01]
3.7.3
pantograph
apparatus for collecting current from one or more contact wires, formed of a hinged device designed to allow
vertical movement of the pantograph head
[IEC 60050-811-32-02]
3.7.4
shoegear
assembly of parts for collecting current from a conductor rail
[IEC 60050-811-32-19]
3.7.5
trolley
apparatus for collecting current from a contact wire by means of a grooved wheel or contact slipper mounted
on a pole which is movable in any direction
[IEC 60050-811-32-08]
3.8
Residual current devices
3.8.1
residual current device (RCD)
mechanical switching device designed to make, carry and break currents under normal service conditions
and to cause the opening of the contacts when the residual current attains a given value under specified
conditions
NOTE
A residual current device can be a combination of various separate elements designed to detect and evaluate the residual
current and to make and break current.
[IEC 60050-442-05-02]
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EN 50122-1:2011
3.8.2
residual current operated circuit-breaker without integral overcurrent protection (RCCB)
residual current operated switching device not designed to perform the functions of protection against
overloads and/or short-circuits
[IEC 60050-442-05-03]
3.8.3
residual current operated circuit-breaker with integral overcurrent protection (RCBO)
residual current operated switching device designed to perform the functions of protection against overloads
and/or short-circuits
[IEC 60050-442-05-04]
3.9
General terms
3.9.1
(electrically) instructed person
person adequately advised or supervised by electrically skilled persons to enable him or her to perceive risks
and to avoid hazards which electricity can create
[IEC 60050-195-04-02]
3.9.2
authorized trackside walking route
safe path alongside the track for use only by authorized persons
3.9.3
monitoring
activity, performed either manually or automatically, intended to observe the state of an item
NOTE
Automatic supervision may be performed internally or externally to the item.
[IEC 60050-191-07-26]
3.9.4
public area
area to which the public has unrestricted access
3.9.5
restricted area
area for which access is only permitted for authorized persons
4
4.1
Contact line zone and current collector zone
Overhead contact line systems
These zones are defined for protective provisions in accordance with 6.3 and are the zones whose limits are
in general not exceeded by a broken overhead contact line or an energised dewired or broken current
collector and its fragments.
Structures and equipment may accidentally come in contact with a live broken overhead contact line or live
parts of a broken or dewired current collector and thereby become live. Figure 1 defines the zone inside
which such contact is considered to be probable.
NOTE 1
A current collector which has become disconnected from the overhead contact line due to a mishap may nevertheless be
alive if a train has multiple current collectors which are electrically connected or if the train is braking using a regenerative brake.
The parameters X, Y, Z in Figure 1 shall be defined by national regulations.
NOTE 2
A guiding value for the parameter X is given as 4 m, Y is given as 2 m and Z is given as 2 m.
NOTE 3
The stagger has been taken into consideration within the dimension of X.
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EN 50122-1:2011
– 18 –
If the current collector is a pantograph the width of the current collector zone Y is the result of:
–
the half width of the pantograph LP/2,
–
the lateral movement of the pantograph S1,
–
the electrical clearance Sel in accordance with EN 50119, and
–
a safety distance S2 for the broken or dewired pantograph.
Y = LP/2 + S1 + Sel + S2
The height of the current collector zone Z depends on:
–
the maximum height of the fully uplifted current collector Hmax measured from the TOR,
–
the electrical clearance Sel in accordance with EN 50119,
–
a safety distance in height S3 for the broken pantograph.
Z = Hmax + Sel + S3 - HP
The point HP is the position of the highest conductor of the overhead contact line under all operational
conditions considered in the centre of the track. The limits of the overhead contact line zone below TOR are
extended vertically downwards until the earth surface is reached.
These limits need not be extended below the upper surface of the deck when the railway runs over a bridge.
In the case of out of running overhead contact lines the overhead contact line zone shall be extended
accordingly.
When it can be proved, that it is unlikely that an overhead conductor rail will break and endanger the
neighbouring area, an overhead conductor rail zone in this context is not necessary, but a current collector
zone is necessary.
The current collector zone for trolleys shall be given in national regulations.
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EN 50122-1:2011
LP
!
S1
Sel
S2
HP
S3
CCZ
Z
Sel
OCLZ
SH
TCL
Hmax
Y
Y
TOR
X
X
Key
TOR
top of rail
HP
highest point of the overhead contact line
OCLZ
overhead contact line zone
CCZ
current collector zone
TCL
track centre line
X
maximum unidirectional (half) horizontal OCLZ, top of rail level
Y
maximum unidirectional (half) horizontal CCZ
Z
distance between HP and SH
S1
width of lateral movement of the current collector
S2
lateral safety distance for the broken or dewired current collector
S3
vertical safety distance for the broken or dewired current collector
Sel
electrical clearance in accordance with EN 50119
SH
maximum height of current collector zone
LP
current collector width
Hmax
maximum height of the fully uplifted current collector
Figure 1 — Overhead contact line zone and current collector zone
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EN 50122-1:2011
4.2
– 20 –
Conductor rail systems
In the case of a conductor rail close to the running rails, a contact line zone is not required.
NOTE
The risk of a broken conductor rail can be neglected.
For provisions against direct contact see 5.5. The limits of the current collector zone shall be stipulated
according to each specific case by the infrastructure manager.
4.3
Trolleybus systems
This zone is defined for protective provisions in accordance with 5.6.3 and is the zone whose limits are in
general not exceeded by one or both broken overhead contact wire or an energised dewired or broken trolley
and its fragments.
Structures and equipment may accidentally come in contact with a live broken overhead contact line or live
parts of a broken or dewired trolley and thereby become live. Figure 2 defines the zone inside which such
contact is considered to be probable.
The parameters X, Y, Z in Figure 2 shall be defined by national regulations.
NOTE
A guiding value for the parameter X is given as 4 m, Y is given as 0,6 m and Z is given as 1 m.
In the case of trolleybuses, the trolley and the current collector head are guided by the contact wire: therefore
the parameters LP and S1 are zero.
The width of the current collector zone Y is the result of:
–
the electrical clearance Sel in accordance with EN 50119, and
–
a safety distance S2 for the broken or dewired trolley.
Y = Sel + S2
The height of the current collector zone Z depends on:
–
the maximum height of the fully uplifted trolley Hmax measured from the road surface;
–
the electrical clearance Sel in accordance with EN 50119;
–
a safety distance in height S3 for the broken current collector.
Z = Hmax + Sel + S3 - HP
The point HP is the position of the highest conductor of the overhead contact line under all operational
conditions. The limits of the overhead contact line zone need not be extended beyond the upper surface of
the deck when the trolleybus-line runs over a bridge.
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EN 50122-1:2011
Sel
S2
S3
CCZ
Z
Sel
HP
OCLZ
BCL
Hmax
Y
Y
RS
X
X
Key
HP
highest point of the overhead contact line
RS
road surface
OCLZ
overhead contact line zone
CCZ
current collector zone
BCL
bifilar centre line
X
maximum unidirectional (half) horizontal OCLZ, top of road surface
Y
maximum unidirectional (half) horizontal CCZ
Z
distance between HP and SH
S2
lateral safety distance for the broken or dewired current collector
S3
vertical safety distance for the broken or dewired current collector
Sel
electrical clearance in accordance with EN 50119
SH
maximum height of current collector zone
Hmax
maximum height of the fully uplifted current collector
Figure 2 — Overhead contact line zone and current collector zone for trolley bus systems
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EN 50122-1:2011
5
– 22 –
Protective provisions against direct contact
5.1
General
According to HD 60364-4-41 no protection against direct contact is required for circuits with nominal voltages
up to and including AC 25 V or DC 60 V. This shall not apply, however, if the circuit concerned is connected
to the traction return circuit.
In overhead contact line systems one of the following protective provisions shall be utilized for protection
against direct contact:
–
protection by clearance;
–
protection by obstacles.
All insulators which are directly connected to a live part shall be regarded as a live part when considering
clearance dimensions in this European Standard. Exceptions are the parts of synthetic ropes which are
further than 2 m (1 m under cover) from the live part.
5.2
Protection by clearance
5.2.1
Standing surface
For standing surfaces accessible to persons, the clearance for touching in a straight line shown in Figure 3
and Figure 4 shall be provided against direct contact with live parts of an overhead contact line system as
well as live parts on the outside of a vehicle (e.g. current collectors, roof conductors, resistors). This does not
apply to conductor rail systems near the running rails (refer to 5.5).
The clearances given in Figure 3 and Figure 4 are minimum values which shall be maintained at all
temperatures and in the full range of electrical and mechanical loads of the conductors. Due to national or
regional existing practices, greater clearances or smaller mesh sizes may be prescribed by the relevant
infrastructure manager.
This protection is not mandatory if, although contact with live parts is possible, other provisions have been
taken to ensure isolation from the supply.
NOTE 1
Touching in a straight line implies that live parts are accessible by a person from a standing surface without use of objects.
NOTE 2
Figure 3 and Figure 4 assumes that the standing surface does not afford protection against contact with live parts situated
below or to the side thereof. Depending on its construction the surface may in practice meet the requirement respecting provision of
obstacles. In this case the lower clearances applicable to obstacles may be applied.
NOTE 3
These clearances have been determined on the basis of the arms reach as defined in HD 60364-4-41 to which a margin of
safety was added. The margin of safety has been determined depending on the voltage of the contact line system, on experience and
on whether the standing surface is in a restricted area or in a public area.
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EN 50122-1:2011
0
R 3,
R 2,
6
Dimensions in metres
3
,45
R
35
1,
R1
2,5
0,5
1
2
Key
1
public areas
2
restricted areas
3
standing surface
Figure 3 — Minimum clearances to accessible live parts on the outside of vehicles
as well as to live parts of overhead contact line systems from standing surfaces accessible
to persons for low voltages
R 3,5
R 2,
75
Dimensions in metres
3
R
5
2,2
R
1,
5
3,0
0,5
1
2
Key
1
public areas
2
restricted areas
3
standing surface
Figure 4 — Minimum clearances to accessible live parts on the outside of vehicles
as well as to live parts of overhead contact line systems from standing surfaces accessible
to persons for high voltages
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EN 50122-1:2011
5.2.2
– 24 –
Exceptions for working persons
The clearances to be observed for persons working near to energised contact line systems shall be defined
in the operational specifications. If operational specifications do not exist, clearances shown in Figure 3 and
Figure 4 or the clearances to obstacles according to 5.3 shall be used.
Standing surfaces or platforms utilized solely for the execution of work at or in the vicinity of the contact line
system are not included.
NOTE
Examples are station platform roofs, working platforms and working planks at signal bridges, working platforms at signals,
maintenance-ladders, work cages of hydraulic working platforms, working platforms of tower cars.
5.2.3
Warning signs
Warning signs shall be used in areas where there is a serious risk of persons coming within the limits of live
parts of a contact line system given in 5.2.1. Such warning signs shall be placed in a prominent position and
be readily visible adjacent to the point of access. The sign shall be in accordance with ISO 3864 (see
Annex B). If required an appropriate supplementary sign may be used.
5.2.4
Minimum height of overhead contact lines above roads
Where a road carrying normal vehicular traffic crosses or coincides with a railway, tramway or trolleybus
electrified by means of an overhead contact line and no road traffic restrictions are specified, unless
otherwise fixed by national regulation, a minimum vertical clearance as stated below shall be provided
between the road surface and the lowest point of the overhead contact line and associated feeders.
The minimum vertical clearance between the road surface and the overhead contact line shall be:
–
for low voltages, 4,70 m;
–
for high voltages, 5,50 m.
If the required minimum clearance cannot be provided and unless otherwise specified by national regulation,
the maximum height of road vehicles permitted to pass under the overhead contact line shall be limited so as
to guarantee the following minimum vertical clearances between the highest point of road vehicle (load
included) and the live parts:
a)
b)
for low voltages:
1)
0,50 m, where only road traffic signs indicating the maximum permissible vehicle height are utilized,
2)
0,30 m, where additional fixed barriers (e.g. a rigid obstacle or a firmly fixed metallic wire made
visible by means of a suspended warning sign) are erected on both sides of the crossing, physically
limiting such vehicle height;
for high voltages:
1)
1,00 m, where only road traffic signs indicating the maximum permissible vehicle height are utilized,
2)
0,50 m, where additional fixed barriers (e.g. a rigid obstacle or a firmly fixed metallic wire made
visible by means of a suspended warning sign) are erected on both sides of the crossing, physically
limiting such vehicle height.
5.2.5
Feeders above loading roads
Feeders or line feeders in high voltage systems should not be situated above loading roads or loading
sidings. When not avoidable, there shall be a minimum vertical distance of 12,00 m between surfaces of the
loading platform (ramps) and feeders.
5.2.6
Clearance between live parts of overhead contact line systems and trees
For railways with high voltage, the distance between the live parts of the overhead contact line system and
branches of trees or bushes shall be at least 2,50 m with no wind or ice loading.
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5.3
EN 50122-1:2011
Protection by obstacles
5.3.1
General
If the clearances given in 5.2.1 to 5.2.5 cannot be maintained, obstacles shall be provided as protection
against direct contact with live parts. The design of obstacles is dependent on the location of the standing
surfaces shown in Figure 5 and Figure 6 relative to the live parts, on the nominal voltage, on the clearance
between the obstacle and the live parts and on whether the standing surface is a restricted area or a public
area.
The dimensions of the obstacles shall be such that live parts cannot be touched in a straight line by persons
on a standing surface.
In case the obstacle is made of conductive material the requirements of 6.2 shall apply.
5.3.2.2
5.3.3.2
1
5.2.2
2
3
5.3.2.1
5.3.3.1
4
5.3.2.1
5.3.3.1
Key
1
catenary wire
2
contact wire
3
feeder
4
working platform
NOTE
The numbers refer to the appropriate subclauses.
Figure 5 — Standing surfaces for persons providing access to live parts on the outside of
vehicles and to overhead contact line systems
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EN 50122-1:2011
– 26 –
5.5.1
NOTE
5.5.2
5.5.3
5.5.5
5.5.6
5.5.7
The numbers refer to the appropriate subclauses.
Figure 6 — Standing surfaces for persons providing access to live parts on the outside of
vehicles and to conductor rail systems
Only obstacles of the following type may be provided:
–
solid walls or solid wall doors;
–
mesh constructions.
Inside the overhead contact line zone and current collector zone the following specifications shall be met by
obstacles:
a)
b)
non conductive obstacles shall be of solid walls or solid wall doors
1)
for systems of high voltages, obstacles within 0,60 m of live parts shall provide earthed frame;
2)
the materials shall be selected so that they will not become conductive as a result of the likely
effects of moisture, ultra-violet radiation, chemical attack and other environmental damage, nor of
contact with live parts.
mesh constructions of plastic coated metal shall not be utilized.
The obstacle shall be constructed to prevent non-intentional (accidental) contact of live parts with parts of the
body. Obstacles shall be fixed mechanically and reliably. They shall only be removable with tools. Obstacles
shall be secured to ensure that the distance to live parts is maintained.
Minimum clearances shall be maintained between obstacles and live parts. The electrical clearance shall
correspond to the relevant clearance as given in EN 50119 to which the following lengths shall be added:
–
0,03 m for solid walls or solid-wall doors, if buckling or warping cannot be excluded;
–
0,10 m for mesh constructions, where no other minimum clearance is given in 5.3.2.1 and 5.3.3.1.
5.3.2
5.3.2.1
Obstacles for standing surfaces in public areas
Obstacles for standing surfaces adjacent to live parts
The clearances shown in Figure 3 and Figure 4 shall be provided for standing surfaces to adjacent live parts
of the outside of the vehicles or live parts of contact line system. If these clearances are not achieved, then,
obstacles shall be provided which shall comply with the following requirements.
If the clearance in height between the top of the obstacle and live parts is at least 1,00 m (see Figure 7 a))
the obstacle shall be of solid-wall design or IP2X according to EN 60529 for low voltage 1,00 m high,
surmounted by a mesh construction with a maximum 1 200 mm² mesh size to an overall height of at least
1,80 m. Such mesh shall be arranged so as to ensure that the obstacle remains unclimbable. If this
clearance is not achieved, the obstacle shall be of solid-wall design (or IP2X for low voltage) 1,80 m high
(see Figure 7 b)). The dimension d between the obstacle and live parts, shown in Figure 7, shall be
determined as described in 5.3.1.
The obstacle shall have no gap to the standing surface.
The top of such obstacles shall be designed so, that it is difficult to stand or to walk on them.
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EN 50122-1:2011
Dimensions in metres
max
(d + x; 1,0)
max
(d + x; 1,0)
1,0 b
h ≥ 1,8
1,8
1,0
≥ 1,0
0,5 a
0,5 a
a)
d+x
b)
d+x
1
2
3
Key
1
solid-wall design or obstacle conforming to protection Class IP2X as defined in EN 60529
2
mesh screen with a maximum 1 200 mm² mesh size (can also be solid-wall design)
3
limit to live parts
d
is the clearance in air between the obstacle and live parts in accordance with 5.3.1
x
is an additional distance:
x = 0 for solid wall design
x = 1,0 for IP2X for low voltage
x = 1,5 for 1 200 mm² mesh size
a
is based on the requirements given in 5.3.2.2.
b
may be reduced by the same extent as the height h exceeds the value of 1,8.
max (d + x; 1,0) means (d + x), but at least 1,0.
Figure 7 — Examples of obstacles for standing surfaces in public areas for protection against
direct contact with adjacent live parts on the outside of vehicles or adjacent live parts of a
contact line system
5.3.2.2
Obstacles and standing surfaces above live parts
Standing surfaces above live parts on the outside of vehicles or above live parts of a contact line system
shall be of solid-wall design.
The length of the solid-walled standing surface shall correspond to the current collector zone and extend
beyond the live parts of a contact line system by at least 0,50 m on each side. In the case of conductors not
being used for current collection (e.g. line feeders, reinforcing feeders, out of running overhead contact lines)
there shall be a width of at least 0,50 m on each side of the conductor provided that movement due to
dynamic and thermal effects has been taken into account.
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EN 50122-1:2011
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Along the sides of these standing surfaces, obstacles shall be provided in order to prevent any direct contact
with live parts on the outsides of vehicles and to live parts of the contact line system even where, for
example, a rod or liquid jet is utilized. These obstacles shall be provided over a length that corresponds at
least to the mandatory length of the standing surface which is in solid-wall design. The obstacles can either
be any construction corresponding to Class IP3X according to EN 60529 or any other construction giving the
same level of safety.
In case of horizontal obstacles extending beyond the vertical obstacle by at least:
–
0,50 m for low voltage,
–
1,50 m for high voltage,
then, in respect of the following:
–
for low voltage a 1,45 m lateral clearance as shown in Figure 3,
–
for high voltage a 2,25 m lateral clearance as shown in Figure 4
it is acceptable to refer them to the top of the vertical obstacle, instead of referring them to the edge of the
standing surface (see Figure A.1 a) for low voltage and Figure A.2 a) for high voltage). The height of the
vertical obstacle shall be consequently increased whenever necessary, in order to achieve this clearance.
The horizontal obstacle shall be designed so that it is difficult to stand or to walk on them.
NOTE 1
To achieve this, the horizontal obstacle should be designed so that it is obviously not a standing surface, or it should be
inclined upwards or downwards (see Figure A.1 a) for low voltage and Figure A.2 a) for high voltage).
Whenever this horizontal obstacle is not present, the vertical obstacle shall conform to the requirements of
5.3.2.1 (see Figure A.1 b) for low voltage and Figure A.2 b) for high voltage). The alternative solution (see
Figure A.1 c) for low voltage and Figure A.2 c) for high voltage) is also acceptable.
The tops of such obstacles shall be designed so that it is difficult to stand or to walk on them.
Any vertical obstacle shall be of solid wall design, or Class IP2X as defined in EN 60529, and at least to a
height of 1,00 m (see Figure A.1 for low voltage and Figure A.2 for high voltage), except in the case of the
above said horizontal obstacle, where a railing is sufficient, if the clearances required by Figure 3 and
Figure 4 are present.
NOTE 2
In addition to the requirements for electrical safety there may be additional requirements for obstacles to provide for security
according to national regulations.
5.3.3
5.3.3.1
Obstacles for standing surfaces in restricted areas
Obstacles for standing surfaces adjacent to live parts
With standing surfaces adjacent to live parts on the outside of vehicles or adjacent to live parts of a contact
line system, obstacles of mesh screens construction with a maximum 1 200 mm² mesh size and having a
height h of at least 1,80 m may be used where the live parts are situated above the standing surface (see
Figure 8 a) for low voltage and Figure 9 a) for high voltage).
If the live parts are situated at the same height or lower than the standing surface, the height h of the
obstacle shall be such that a clearance of:
–
for low voltage 1,35 m,
–
for high voltage 1,50 m,
from the top of the obstacle is maintained as shown in Figure 3 (see Figure 8 b) for low voltage) and Figure 4
(see Figure 9 b) for high voltage).
The clearance between the obstacle and the live parts shall be at least:
–
for low voltage 0,30 m,
–
for high voltage 0,60 m.
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EN 50122-1:2011
If this clearance is not maintained, the obstacles shall be designed in accordance with 5.3.4 for low voltage
or be of solid-wall design and leave no gap between the obstacle and the standing surface (see Figure 8 c)
and Figure 8 d) for low voltage and Figure 9 c) and Figure 9 d) for high voltage). The dimension d between
the obstacle and live parts, shown in:
–
for low voltage in Figure 8, and
–
for high voltage in Figure 9,
shall be determined as described in 5.3.1.
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EN 50122-1:2011
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Dimensions in metres are minimum dimensions
0,3
0,3 c
h ≥ 1,8
h ≥ 1,8
0,3
a)
d
c)
1,35 a
1,35 a
h
h
d
b)
d)
0,5 b
0,3
1
2
3
Key
1
solid-wall design or obstacle confirming to protection Class IP2X as defined in EN 60529
2
mesh screen with a maximum 1 200 mm² mesh size (can also be solid-wall design)
3
limit to live parts
d
is the clearance in air between the obstacle and live parts in accordance with 5.3.1
a
is derived from Figure 3
b
is based on the requirements given in 5.3.3.2
c
may be reduced by the same extent as the height h exceeds the value of 1,8 m
Figure 8 — Examples of obstacles for standing surfaces in restricted areas for protection
against direct contact with adjacent live parts on the outside of vehicles or adjacent live parts
of a contact line system for low voltages
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EN 50122-1:2011
Dimensions in metres are minimum dimensions
0,6
0,6 c
h ≥ 1,8
h ≥ 1,8
0,6
d
a)
c)
d
1,5 a
1,5 a
h
h
d
b)
d)
0,5 b
0,6
1
2
3
Key
1
solid-wall design or obstacle confirming to protection Class IP2X as defined in EN 60529
2
mesh screen with a maximum 1 200 mm² mesh size (can also be solid-wall design)
3
limit to live parts
d
is the clearance in air between the obstacle and live parts in accordance with 5.3.1
a
is derived from Figure 4
b
is based on the requirements given in 5.3.3.2
c
may be reduced by the same extent as the height h exceeds the value of 1,80 m
Figure 9 — Examples of obstacles for standing surfaces in restricted areas for protection
against direct contact with adjacent live parts on the outside of vehicles or adjacent live parts
of a contact line system for high voltages
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EN 50122-1:2011
5.3.3.2
– 32 –
Obstacles for standing surfaces above live parts
For standing surfaces above live parts on the outside of vehicles or above live parts of a contact line system,
the obstacles shall be designed according to 5.3.4 for low voltage or shall be solid-wall design (see
Figure 10 a) and Figure 11). If the clearance between the obstacles and the live parts is at least 0,60 m for
low voltage, walkways which include a mesh construction with a maximum 1 200 mm² mesh size, may be
provided as obstacles (see Figure 10 b)).
The length of the solid-walled or mesh construction standing surface shall correspond to the current collector
zone and extend beyond the live parts of a contact line system by at least 0,50 m on each side. In the case
of conductors not being used for current collection (e.g. line feeders, reinforcing feeders, out of running
overhead contact lines) there shall be a width of at least 0,50 m on each side of the conductor provided that
movement due to dynamic and thermal effects has been taken into account.
Obstacles of mesh screen construction with a maximum 1 200 mm² mesh size shall be at least provided at
the sides of such standing surfaces. The height h of the obstacles shall be such that a clearance of:
–
for low voltage 1,35 m as shown in Figure 3 (see Figure 10 a) and Figure 10 b));
–
for high voltage 1,50 m as shown in Figure 4 (see Figure 11);
from the top of the obstacles is maintained. These obstacles shall be at least as long as the length of the
standing surface above live parts.
NOTE
The height of the side obstacles, if necessary, will generally correspond to the height of the necessary safety railing but
should have a height of at least 1,00 m.
The dimension d between the obstacle and live parts, shown in Figure 10 and Figure 11, shall be determined
as described in 5.3.1.
Dimensions in metres are minimum dimensions
h
1,35 a
h
1,35 a
d
0,6
0,5 b
0,5 b
a)
b)
1
2
3
Key
1
solid-wall design or obstacle confirming to protection Class IP2X as defined in EN 60529
2
mesh screen with a maximum 1 200 mm² mesh size (can also be solid-wall design)
3
limit to live parts
d
is the clearance in air between the obstacle and live parts in accordance with 5.3.1
a
is derived from Figure 3
b
is based on the requirements given in 5.3.2.2
Figure 10 — Examples of obstacles for standing surfaces in restricted areas for protection
against direct contact when above live parts on the outside of vehicles or live parts of a
contact line system for low voltage
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EN 50122-1:2011
Dimensions in metres are minimum dimensions
h
1,5 a
d
0,5 b
1
2
3
Key
1
solid-wall design or obstacle confirming to protection Class IP2X as defined in EN 60529
2
mesh screen with a maximum 1 200 mm² mesh size (can also be solid-wall design)
3
limit to live parts
d
is the clearance in air between the obstacle and live parts in accordance with 5.3.1
a
is derived from Figure 4
b
is based on the requirements given in 5.3.3.2.
Figure 11 — Examples of obstacles for standing surfaces in restricted areas for protection
against direct contact when above live parts on the outside of vehicles or live parts of an
overhead contact line system for high voltage
5.3.4
Protection degree for obstacles for low voltage
For low voltages the obstacles shall meet the requirements for protection degree IP2X according to
EN 60529 with a minimum distance to live parts of 0,50 m or shall be of solid wall design.
5.3.5
Anti climbing provisions
Anti-climbing provisions are not normally necessary. In justified cases however, anti-climbing provisions can
become necessary.
5.4
5.4.1
Protective provisions for working under live conditions
General
This European Standard considers protective provisions for working under live conditions in low voltage
systems only.
The electrical installation shall be constructed and installed to ensure that the measures necessary for the
protection of persons working in or on electrical installations can be employed. The rules for operation and
maintenance of electrical power installations shall also be taken into account in the design. The working
procedures shall be agreed on between manufacturer and user.
This does not apply to locations for which this requirement is technically impossible, e.g. for section
insulators, crossing points of overhead contact lines of tramways and trolleybuses and for trolleybus
overhead contact lines.
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EN 50122-1:2011
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NOTE
This requirement can be met, for example, by installation of additional insulation in the overhead contact line system to
achieve neutral sections each at least 0,50 m long, which ensure that simultaneous contact with different potentials in the immediate
working area is obviated completely or to a considerable extent.
Insulators whose design is such that supporting structures may become live under fault conditions (e.g.
saddle insulators or buckle insulators) shall not be utilized for the overhead contact line system where live
working shall be undertaken.
5.4.2
Overhead contact lines for railways or tramways beneath structures
In the case of overhead contact lines suspended beneath structures (tunnels, underpasses) where work is to
be executed from an insulated platform whilst the line is energised, insulated obstacles or obstacles
insulated with respect to the structure of minimum width 1,00 m shall be provided on both sides of the track
centre if the clearance to structural elements connected to earth is less than 1,00 m (see Figure 12). These
obstacles shall be 0,50 m longer than the edge of the structure.
Dimensions in metres
0,5
6
<1,0
5
1
3
2
1,0
1,0
1
4
Key
1
contact wire
2
insulated obstacle
3
stagger
4
track centre
5
insulated arm
6
support
NOTE
The stagger has been taken into consideration within the dimension of 1,00 m.
Figure 12 — Example of an insulated obstacle beneath a structure
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5.4.3
5.4.3.1
EN 50122-1:2011
Overhead contact lines for trolley bus systems beneath structures
Unearthed systems
In the case of overhead contact lines suspended beneath structures (tunnels, underpasses) where work is to
be executed from an insulated platform whilst the line is energised, insulated obstacles or obstacles
insulated with respect to the structure of minimum width 1,00 m shall be provided on both sides of the centre
line of the contact wires if the clearance to structural elements connected to earth is less than 1,00 m (see
Figure 13). These obstacles shall be 0,50 m longer than the edge of the structure.
Dimensions in metres
0,5
6
<1,0
5
1
2
1
1,0
1,0
4
Key
1
contact wire
2
insulated obstacle
4
bifilar centre line
5
insulated arm
6
support
NOTE
According to EN 50119 the distance between the contact wires is normally 0,60 m or 0,70 m.
Figure 13 — Example of an insulated obstacle beneath a structure
for an unearthed trolley bus system
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EN 50122-1:2011
5.4.3.2
– 36 –
Systems in which one of the contact wires is earthed or connected to the return circuit of a
tramway system
In the case of overhead contact lines suspended beneath structures (tunnels, underpasses) where work is to
be executed from an insulated platform whilst the line is energised, insulated obstacles or obstacles
insulated with respect to the structure of minimum width 0,65 m shall be provided on both sides of the
unearthed contact wire if the clearance to structural elements connected to earth is less than 1,00 m (see
Figure 14). These obstacles shall be 0,50 m longer than the edge of the structure.
Dimensions in metres
0,5
6
<1,0
5
1
2
0,65
4
0,65
1
7
Key
1
contact wire
2
insulated obstacle
4
bifilar centre line
5
insulated arm
6
support
7
positive contact wire line
NOTE
According to EN 50119 the distance between the contact wires is normally 0,60 m or 0,70 m.
Figure 14 — Example of an insulated obstacle beneath a structure for a trolley bus system in
which the negative contact wire is earthed or connected to the return circuit of a tramway
system
NOTE
5.5
5.5.1
Figure 14 also applies in case of earthed positive contact wire, in which case “+” and “-“ should be exchanged.
Specific protective provisions against electric shock in conductor rail systems
Location of conductor rail at platforms
Conductor rails shall be on the side of the track away from the platform wherever practical. This applies to all
cases except where a single track lies between two platforms.
5.5.2
Exceptions
The requirements given in 5.3.3 can be waived in case of vehicles with shoegear for conductor rails if the
shoegear does not extend considerably outside the vehicle gauge. In depots the internal operational ways
shall be clearly distinguishable.
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5.5.3
EN 50122-1:2011
Protection provisions in workshops
For workshops where it may be impracticable to place a protective boarding around the conductor rail, a
conductor rail system shall not be used. A trolley system or other systems shall be used for supplying the
vehicle. In this case, national or locally defined working practices shall ensure safety around any live parts of
a vehicle energised in a workshop, such as shoegear.
5.5.4
Protective boarding for conductor rails in restricted areas
In the case of bottom-contact conductor rail systems, the surface of the conductor rail not touched by the
current collector shall be protected by means of protective boarding.
In the case of side contact conductor rail systems, the top and side surface not touched by the current
collector shall be protected by means of protective boarding.
5.5.5
Requirements for top contact conductor rails in public areas
Anti–trespassing guards constructed of non-conductive material shall be installed parallel to the track for a
distance of # 2,00 m when measured along the line of the track, at both public and private level crossings.
The conductor rail shall be terminated 0,30 m from the edge of the anti-trespassing guard (see Figure 15).
Dimensions in metres
1
2
3
>0,3
>2,0
>2,0
>0,3
Key
1
anti-trespassing guard
2
running rails
3
conductor rail
Figure 15 — Public level crossing, private level crossing
Anti-trespassing guards shall comprise a surface difficult for persons and animals to walk upon.
At public level crossings provided with gates that are protected in accordance with 5.3.2.1 except for the
necessary clearance between the gate and the standing surface and which prevent access to the railway
when the road is open, the conductor rail shall be terminated 0,30 m from the edge of the crossing. No antitrespassing guards or protective boarding are required.
At private level crossings provided with gates in accordance with the paragraph above and which prevent
public access to the railway, the conductor rail shall be terminated 0,30 m from the edge of the crossing.
Double protective boarding shall be provided for a minimum distance of 2,00 m.
NOTE
Different sets of requirements apply for public and private level crossings because of differences in operational use.
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EN 50122-1:2011
5.5.6
– 38 –
Requirements for top contact conductor rails in restricted areas
For top contact conductor rail systems the following requirements apply:
Where the egress from a building or an equipment location facing towards the track is within 1,00 m of the
conductor rail and no physical barrier is provided, then single protective boarding shall be provided on the
outside of the conductor rail, extending 1,00 m either side of the location (see Figure 16).
Dimensions in metres
2
1
1,0
4
>1,0
>1,0
3
>1,0
5
>1,0
Key
1
single protective boarding
2
running rails
3
conductor rail
4
cabin and steps
5
box and door
Figure 16 ! Trackside structures
At signal-post telephone locations double protective boarding shall be provided for a distance of 8,00 m,
commencing 7,00 m on the approach side of the signal-post with telephone (see Figure 17).
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EN 50122-1:2011
Dimensions in metres
2
1
4
>1,0
3
>7,0
Key
1
double protective boarding
2
running rails
3
conductor rail
4
signal with telephone
Figure 17 — Signal-post with telephone
If the telephone and the signal post are not at the same location, the location of the telephone shall be used
for the projection of the protective boarding.
Where an authorized trackside walking route is located within 2,00 m of a conductor rail and no physical
barrier is provided, then single protective boarding shall be provided on the outside of the conductor rail,
extending 1,00 m either side of the end of the route (see Figure 18).
Dimensions in metres
2
2,0
3
1
>1,0
>1,0
Key
1
single protective boarding
2
running rails
3
conductor rail
Figure 18 — Authorized trackside walking route
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EN 50122-1:2011
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For railway controlled crossings the conductor rail shall be terminated 2,00 m from the crossing with double
protective boarding provided for a minimum distance of 2,00 m (see Figure 19).
Dimensions in metres
2
3
1
>2,0
>2,0
>2,0
>2,0
Key
1
double protective boarding
2
running rails
3
conductor rail
Figure 19 — Railway controlled crossing (depots, goods yard, station crossing)
5.6
Specific protective provisions against electric shock in systems in which the wheels
of the vehicles are not used for return circuit
5.6.1
General
This clause applies to systems which employ an insulated conductor for the return circuit so that the traction
current does not flow in the running rails in normal conditions. Examples are “Third and Fourth Rail” d.c.
conductor rail systems, and some kinds of three-phase a.c. systems or monorail systems and trolleybuses.
5.6.2
5.6.2.1
Railway systems
Use of the running rails as protective earth connection of vehicles
If the design of the vehicles is such that a fault on a live part of a vehicle equipment can connect a contact
line or a return conductor to the running rails, then the substation equipment shall isolate automatically every
earth fault which is not isolated by the equipment of the vehicles. See also 10.3.1.
5.6.2.2
Systems in which the vehicles do not require to be connected electrically to the running
rails
If the equipment of the vehicles is designed so that no fault on a vehicle will connect a contact line to
exposed conductive parts of the vehicle, and a connection from the vehicles to earth via the running rails is
not required, 5.6.3.2 shall apply. In addition, earth faults on the contact lines shall be isolated within a
sufficiently short time, to reduce to the lowest practical level the risk that multiple earth faults would cause
impermissible touch voltages or thermal overload of the bonding conductors and related items.
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5.6.3
EN 50122-1:2011
Trolleybus systems
5.6.3.1
General
The insulation of each contact wire shall be appropriate to the nominal voltage of the system according to
EN 50163.
5.6.3.2
Unearthed systems
Unearthed overhead contact lines shall have an insulation monitoring device for monitoring the state of the
insulation between each contact wire and earth.
Whenever a feeding section has to be de-energised both contact wires shall be switched off. Sequential
switching is permitted.
5.6.3.3
Earthed systems
In case of one of the both contact wires is earthed, the following conditions shall be fulfilled:
–
whenever a switching device is installed in the earthed wire, another switch shall be installed in the other
wire, and the switching device shall be interlocked so that it cannot be opened before the supply switch
is open,
–
it shall only be earthed at one point per feeding section which shall be insulated from other feeding
sections.
Return cables shall conform to the requirements given in 10.3.1.
5.6.3.4
Trolleybus power supply connected to the power supply of a tramway
In case of a common traction power supply system for a trolleybus system and a tramway system, the
following conditions shall be fulfilled:
–
one contact wire trolleybus system shall be connected without any disconnection to the return circuit of
the tramway system;
–
in case a switching device is installed in the wire connected with the tramway return circuit, another
switch shall be installed in the other wire, and the switching device shall be interlocked so that it cannot
be opened before the supply switch is open;
–
the trolleybus return circuit shall be connected at least once to the return circuit of the tramway system.
NOTE 1
Feeding sections for trolleybus and tramway should be separated one from the other and supplied by different circuit
breakers inside substations.
NOTE 2
The additional return current of the tramway system in the return system of the trolleybus system and visa versa has to be
considered.
6
6.1
Protective provisions against indirect contact and impermissible rail potential
Protective provisions against indirect contact
Provisions for protection against indirect contact shall be provided for exposed conductive parts and for
components of contact line systems.
In traction systems connection to the return circuit is the preferred method to achieve electrical safety.
NOTE
of supply.
This method uses the return circuit for conduction of the current under fault conditions and causes automatic disconnection
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EN 50122-1:2011
6.2
– 42 –
Protective provisions for exposed conductive parts within the contact line zone or the
current collector zone
6.2.1
A.C. traction systems
Exposed conductive parts of traction and non traction power supply which are located within the contact line
or the current collector zone shall be directly connected to the return circuit.
NOTE
Connection to the running rails or to the return conductor is the preferred method to achieve this.
If it is determined that one of the running rails or exposed conductive parts cannot be directly connected to
the return circuit (e.g. track circuits), then a voltage-limiting device (minimum functionality VLD-F) shall be
used to provide a path for the current in the event of these running rails (insulated rails) or exposed
conductive parts becoming live.
6.2.2
6.2.2.1
D.C. traction systems
General
Exposed conductive parts of traction and non traction power supply which are located within the contact line
zone or the current collector zone and which are not insulated from earth shall not be bonded directly to the
return circuit due to the effects of stray current corrosion, see EN 50122–2. Then a voltage-limiting device
(minimum functionality VLD-F) shall be used to make an open connection from the exposed conductive parts
to the return circuit to create a short-circuit path and in consequence to cause the interruption of the current
in a short time to keep the voltage within the limits given in Table 6 or in 9.3.2.3.
All voltage-limiting devices shall be applied in accordance with Annex F.
6.2.2.2
Exceptions in tunnels
For overhead contact line systems up to and including DC 3 kV, and where permitted by national regulations,
an exception to the requirements given in 6.2.2.1 may be allowed for the metallic supports of the overhead
contact line suspensions in tunnels outside the zone shown in Figure 4. This exception requires the use of
insulators, restoring their dielectric property even after a flashover.
It is permitted, that such metallic parts which are normally inaccessible may not be earthed. This is due to the
characteristics of such insulators and to increase maintainability, which is often difficult in tunnels. In this
case the clamping of the metallic supports to the tunnel vault shall be achieved by using a grout having a
good insulating property.
Where national regulations allow to perform maintenance work on structures adjacent to live parts,
provisions in accordance with 5.2.2 shall apply considering the supports with floating potential are also live
parts.
6.2.3
6.2.3.1
Exceptions for low voltage traction systems
General
The following exceptions to 6.2.2 are permissible, provided that all risks of electric shock are considered and
reduced to acceptable levels as defined by national regulations.
6.2.3.2
Double or reinforced insulation of overhead contact line
Supporting structures including masts for overhead contact line systems need not be earthed and need not
be connected to the return circuit if the insulation of the overhead contact line has been doubled or
reinforced as defined in EN 61140. The instructions and procedures for maintenance shall ensure, that
insulators which are defective or bridged by extraneous objects or materials shall be made good promptly so
that no structure will become alive and dangerous due to an ineffective insulator.
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6.2.3.3
EN 50122-1:2011
Bonding of overhead contact line supports to the return circuit
If the supporting structures of a DC railway with low voltage are bonded to the return circuit in contradiction
to 6.2.2 the structures shall be insulated from earth. The insulation shall be proved by measurements.
NOTE
For the conductance per unit length of the return circuit and structures connected to it see EN 50122–2.
6.2.3.4
Precautions against the failure of conductor rail insulators
Precautions shall be taken so that no conductor rail will become connected to earth so as to cause
impermissible touch voltages on the running rails, or cause a risk of fire or thermal damage to equipment. In
particular the risks shall be considered of spurious connections between the conductor rail and the base
plates and fixing bolts of the conductor rail insulators. If the base-plates are not open connected in
accordance with 6.2.2, other precautions shall be applied in order to limit the risks to acceptable levels in
accordance with national regulations, such as:
–
regular cleaning of the insulators;
–
prompt removal of rubbish, especially conductive rubbish, from the tracks;
–
double or reinforced insulators as defined by EN 61140;
–
reliably insulating the base plates and fixing bolts from the earth, for example by mounting them on
wooden blocks;
–
use of insulating shrouds to protect the base plates against contact with the conductor rails through
extraneous objects.
6.2.4
Anchors of wooden masts
An insulator shall be installed in the anchor of wooden masts external to the zone as shown in Figure 3 and
Figure 4 where the supporting structures of the overhead contact line system are not connected to the return
circuit.
6.3
Protective provisions for wholly or partly conductive structures
6.3.1
Structures in the overhead contact line zone or the current collector zone
6.3.1.1
Protective provisions by means of connection to the return circuit
The protective provisions of 6.2 shall be applied to metallic structures to ensure that there is no remaining
dangerous touch voltage.
NOTE 1
–
Such metallic structures are e.g.:
signal gantries and signal posts;
–
bridges;
–
the awnings of station platforms;
–
pipes;
–
fences;
–
huts and equipment enclosures;
–
running rails of non-electric traction systems.
NOTE 2
An example for partly conductive structures is a steel reinforced concrete structure.
The metallic reinforcement of concrete structures shall be treated in the same way as metallic structures
except for structures for which both of the following conditions apply:
–
the structure is not able to transfer a dangerous potential from the fault-location;
–
the probability of contact with a live part is so low that the risk is accepted, that the overhead contact
system or the structure may be damaged if the fault is not interrupted in a sufficiently short time.
These protective provisions shall be harmonized with the provisions specified for d.c. traction systems as
defined in EN 50122–2 for reduction of corrosion due to stray currents.
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EN 50122-1:2011
6.3.1.2
– 44 –
Exceptions for small conductive parts
For conductive parts of small dimensions it is not necessary to take any protective provisions provided the
following conditions and the conditions in Table 1 are fulfilled:
–
the part does not support or contain electrical equipment or it contains only electrical equipment in
conformity with Class II, refer to 7.3.2;
–
a person approaching it from any direction can see if a live conductor is touching the part.
Table 1 — Maximum dimensions for small conductive parts
Dimensions in metres
Type of
conductive parts
Low voltage
High voltage
Parallel to track
Horizontal,
right angle to track
Parallel to track
Horizontal,
right angle to track
wholly conductive
15
2
3
2
partly conductive
15
2
15
2
NOTE 1
This excludes items utilized for protective provisions given in 6.2 and 7.3.
NOTE 2
Small conductive parts are for example: gully covers, signal posts, level crossing posts, individual masts, warning labels,
trash cans, fences, mesh constructions and metallic structures with maximum length as given in Table 1.
The minimum distance between two or more small conductive parts shall be greater than the electrical
clearance given in EN 50119. The electrical insulation between these parts shall be ensured.
6.3.1.3
Exceptions for temporarily stored parts close to the rails
These protective provisions are not required for conductive materials temporarily stored in the vicinity of the
track, e.g. running rails unless required by the operational specifications.
6.3.1.4
Protective provisions by means of obstacles
Instead of the protective provisions given in 6.2 specified for conductive structures or conductive structural
components located in the current collector zone or overhead contact line zone, an obstacle may be
installed. The obstacle shall be situated between the overhead contact line and the structures or structural
components and shall have a width at least equivalent to that of the current collector and overhead contact
line zone and should extend by at least 0,50 m beyond the end of the structure or structural component. The
obstacle shall fulfil the insulation requirements of protection Class II or shall be connected to return circuit.
In cases when the current collector is guided by the overhead contact line (e.g. trolleybus), the current
collector zone width may be reduced by extending the obstacle downwards on both sides of the overhead
contact line by at least 0,05 m below the overhead contact line.
6.3.2
Parts in the vicinity of the railways
Conductive parts which are liable to become live due to inductive or capacitive coupling with the voltage of
the contact line shall be connected to earth if not directly connected to the return circuit.
This applies to:
a)
metallic fences, sign boards and so on, which are installed along the railway line,
b)
parts in the overhead contact line zone or the current collector zone, when the connection to the return
circuit is:
1)
exempted because of small dimensions,
2)
not direct.
NOTE
Earthing via the foundations of such parts is usually sufficient, as long as no intentional insulating joints are inserted.
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6.4
EN 50122-1:2011
Limitation of rail potentials
6.4.1
A.C. systems
If continuous or permanent earthing of the return circuit is not possible, the a.c. system shall nevertheless be
designed and constructed so that the touch voltages do not exceed the levels specified in 9.2. If compliance
with 9.2 is not achieved, the general public shall be protected against contact with the voltage on the return
circuit, and employees shall not be permitted to approach the running rails and the trains except in
accordance with procedures which shall comply with national regulations concerning the safety of instructed
persons.
6.4.2
D.C. systems
In order to avoid impermissible effective touch voltage, in certain cases voltage-limiting devices (minimum
functionality VLD-O, see Annex F) shall be installed e.g. in passenger stations to achieve equipotential
bonding between return circuit and earth.
If in depots, workshops, and industrial d.c. railway systems (e.g. surface coal mining) protection against
impermissible touch voltage can only be achieved by direct earthing of the running rails, increased stray
currents occur. The risks from stray currents shall be considered in accordance with EN 50122–2.
7
7.1
Protective provisions for low voltage non traction power supplies
General
This clause applies to low voltage non traction power supplies which are characterized by being able, under
particular circumstances, to transfer a dangerous voltage over long distances. Therefore an electrical
connection to non railway earthing systems is not desirable. In case of a connection, an agreement is
necessary between the railway side network infrastructure owner and the owner of the other network
infrastructure. Care shall be taken to address transferred potentials and overheating of cables (see 10.2).
The following provisions apply to those low voltage power supplies, where parts of such installations or the
respective structure (earth) is likely to have connection to the return circuit of the railway system. This shall
be assumed for:
–
railways where the structure earth or parts of it are connected to the return circuit,
–
d.c. railways where the structure earth or parts of it are connected to the return circuit via a voltagelimiting device (VLD),
–
d.c. railways where stray currents in the structure earth or parts of it are likely,
–
electrical installation within overhead contact line zone and/or current collector zone.
NOTE 1
–
Following installations are endangered for example:
consumer installations,
–
railway signalling or traffic lights installations,
–
lighting systems,
–
low voltage non traction power supplies,
–
remote control equipment.
NOTE 2
The above installations could be endangered by:
–
a broken overhead contact line or a broken or dewired current collector which can transfer the overhead contact line voltage in
these installations when they are located in the overhead contact line zone or the current collector zone, or when they have
conductive connections to installations which are located in these zones,
–
traction return currents, which can overload protective conductors, PEN-conductors, or which can impair protective provisions
where exposed conductive parts are intentionally and functionally connected to the return circuit.
According to HD 60364-4-41 protection against indirect contact for nominal voltages up to AC 50 V/DC 120 V
shall be provided unless the relevant requirements as defined in HD 60364-4-41:2007, 411.1 are met.
Conductive parts carrying electrical equipment (excluding protection Class II) within the overhead contact
line and current collector zone shall not be considered as parts of small dimension as given in 6.3.1.2.
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EN 50122-1:2011
7.2
– 46 –
Related provisions
The following protective provisions as given in 7.3 and 7.4 shall apply for stationary electrical installations as
given in 7.1 in addition to provisions required by other relevant standards. These protective provisions shall
be harmonized with the provisions specified for d.c. traction systems as defined in EN 50122-2 for reduction
of effects due to stray currents.
7.3
Protective provisions for electrical installations in the overhead contact line zone or
the current collector zone
7.3.1
Exposed conductive parts
Exposed conductive parts within the overhead contact line zone or the current collector zone shall be
connected directly or via a voltage limiting device (VLD-F, see Annex F) to the return circuit, or otherwise be
protected by a robust obstacle. If the obstacle is not made of insulating material, it shall be connected to the
return circuit. In d.c. traction systems such obstacles shall conform to the requirements as defined in
EN 50122-2.
The PE conductors of the electrical installation shall be of sufficient cross-sectional area, so that they will not
be overheated by the portion of the current in the return circuit which can flow in them. The design of the
return circuit and the equipotential bonding shall be coordinated with the insulation levels of the power supply
cables and communications cables connected to electrical equipment which is in the overhead contact line
zone or the current collector zone, or is for other reasons bonded to the return circuit, so that the cables and
installations will not be damaged if there is an earth fault on the contact line system.
7.3.2
Equipment of protection Class II
If electrical equipment of protection Class II in accordance with EN 61140 is utilized then its enduring
temporary overvoltage shall correspond to the nominal voltage of the contact line.
NOTE 1
EN 60664-1:2007, 3.3 defines temporary overvoltages for low voltage equipment.
Such equipment shall not be connected to a PE conductor.
For small conductive parts, carrying protection Class II equipment, the exceptions of 6.3.1.2 still apply.
In case of the use of protection Class II equipment of which the protective provisions do not correspond with
the nominal contact line voltage then the requirements for exposed conductive parts within overhead contact
line zone and current collector zone shall be fulfilled.
NOTE 2
7.4
7.4.1
Protection Class II equipment for high voltage systems is not practical due to economical reasons.
Protective provisions for installations which are endangered by the traction power
supply return circuit
Design of auxiliary power supply
Protection against indirect contact for equipment or installations which are not protection Class II shall be
realized by automatic disconnection of supply as described in HD 60364-4-41.
Exposed conductive parts shall be connected to a protective conductor.
NOTE 1
HD 60364-4-41 distinguishes installations by the kind of earth connection. For railway applications, fixed installations the
TN-system and the TT-system are relevant.
Auxiliary supplies are usually fed by high voltage grid, public low voltage grid or by the traction power supply.
Table 2 shows different kinds of auxiliary supplies and its characteristic connection to earth on railway side.
Additionally the applicable low voltage distribution system on railway side with the respective precondition is
indicated.
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EN 50122-1:2011
Table 2 — Kinds of auxiliary supplies
Supplier side
Kind of supply
Public low voltage
High voltage
7.4.2
Earth and/or neutral from nonrailway earthing installations
Earth and/or neutral from nonrailway earthing installations
Traction
power supply
NOTE 2
Characteristic
Neutral connected to return
circuit or railway owned
structure earth
Railway side
Applicable system
Precondition
TT system
RCD
TN system
Separate winding transformer
TN system
Auxiliary high voltage
transformer located on railway
owned structure earth
TT system
Auxiliary high voltage
transformer not located on
railway owned structure earth
and RCD
TN system
Auxiliary transformer located on
railway owned structure earth
or d.c./a.c. converter
Other kinds of design, e.g. IT system, are allowed.
Low voltage power supply by TT system
All exposed conductive parts collectively protected by the same protective device shall be connected,
together with the protective conductors, to an earthing system common to all those parts.
The supply may come from public LV supply without isolating transformer.
The incoming neutral conductor (PEN as well as N and PE separate) of the supplying non-railway system is
connected to remote earth. In the railway distribution panel this neutral shall be applied as N only. The
incoming PE shall be terminated at an insulated busbar and shall not be used on the railway side. The PE is
derived from the MEB, which is connected to railway owned structure earth.
The resistance to earth RA measured at the MEB shall fulfil the following requirement
RA ≤ U / Ia
where
U
is in general the nominal line-to-earth voltage U0 and in case of protection by RCD it is 50 V
according to HD 60364-4-41;
Ia
is the current, which leads to the automatic tripping of the protective device within 0,4 s.
NOTE 1
For circuit breaker this current depends on the tripping characteristic whereby for characteristic A the tripping current
Ia = 3 x IN (nominal current), for characteristic B: Ia = 5 x IN; for characteristic C: Ia = 10 x IN; for characteristic D: Ia = 20 x IN (see
HD 60364-4-41 and EN 60898-1); e.g. for a circuit breaker with B characteristic and a nominal current of 16 A, a maximum earth
resistance of 230 V/(16 A x 5) = 2,88 ! is required.
NOTE 2
When the protective device is a residual current protective device, Ia is the rated residual operating current I$n. (see
HD 60364-4-41).
NOTE 3
Exceptions are possible for electric circuits with permanently installed equipment only.
The installation of RCDs is basically recommended. If the resistance to earth of the MEB is not low enough,
RCDs shall be applied.
If the equipment is outside the overhead contact line zone and outside the current collector zone and if it has
a connection to the main equipotential busbar, then the PE conductor incorporated in the power supply cable
need not be connected to the exposed conductive part of the equipment.
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EN 50122-1:2011
7.4.3
– 48 –
Low voltage power supply by TN system
All exposed conductive parts of the installation shall be connected to the earth connection point of the LVtransformer windings by protective conductors which shall be earthed at or near each relevant transformer or
generator.
In order to prevent the transfer of dangerous voltages or currents, separations between public earth and the
railway owned structure earth are preferred. In case of separation, transformers with separate windings are
required for the application of the TN system.
The supply may come from:
–
public LV supply via transformer with separate windings;
–
HV supply via auxiliary transformer.
The incoming non-railway earth shall be terminated at an insulated busbar and shall not be used on the
railway side. The star point on the secondary winding of the transformer and its frame (exposed conductive
part) shall be connected to the MEB.
NOTE
In special cases it can be necessary to connect the frame to the public earth via the PE conductor or screens of incoming
cables. Then an insulation between transformer frame and the railway owned structure earth is necessary.
For auxiliary transformers, which primary windings are fed from traction voltage, the neutral points on primary
and secondary side shall be connected to the railway owned structure earth.
The low voltage protection system shall be a TN-S system. RCDs are recommended in the final circuits of
distribution. Overcurrent protective devices shall be applied according to HD 60364-4-41. The maximum
disconnecting times for TN-systems shall be kept.
If the equipment is outside the overhead contact line zone and outside the current collector zone and if it has
a connection to the main equipotential busbar, then the PE conductor incorporated in the power supply cable
shall not be connected to the exposed conductive part of the equipment.
7.4.4
7.4.4.1
Special provisions
A.C. railways
The running rails of a.c. railways are connected to the structure earth consisting of mast foundations,
slabtrack reinforcement and foundations of other wayside structures like tunnels and viaducts. Due to
signalling constraints the connection can contain e.g. impedance bonds. Running rails and main
equipotential busbar of the auxiliary power supply system shall be connected together. For equipment within
the overhead contact line zone and current collector zone the PE conductor shall be able to carry the
maximum short-circuit current. If this is not possible a direct connection to the return circuit shall be carried
out. In this case the PE conductor shall not be connected to the exposed conductive part of the equipment.
Overcurrent protective devices shall also be applied in the neutral conductor for electric circuits without RCD,
i.e. circuit breaker with two- or four-protected poles according to EN 60898-1, if the rail potential is > 50 V. In
case of a tripping, all conductors shall be switched-off simultaneously. Fuses shall not be used.
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EN 50122-1:2011
Figure 20 shows the provisions for a TT system and Figure 21 for a TN system applied in an a.c. railway
system.
1
2
L1
L2
L3
N
PE
10
5
RCCB
I >> I >> I >>
6 7 8
3
9
RCCB
M
4
Key
1
electricity supply network
6
water and gas pipes
2
railway network
7
heating
3
public earth
8
lightning protection
4
overhead contact line and current collector zone
9
railway structure earth
5
MEB
10
only required for rail potential > 50 V
Figure 20 — TT system for a.c. railways
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EN 50122-1:2011
1
– 50 –
2
L1
L2
L3
N
PE
10
5
RCCB
I >> I >> I >>
6 7 8
3
9
RCCB
M
4
Key
1
electricity supply network
6
water and gas pipes
2
railway network
7
heating
3
public earth
8
lightning protection
4
overhead contact line and current collector zone
9
railway structure earth
5
MEB
10
only required for rail potential > 50 V
Figure 21 — TN system for a.c. railways
NOTE 1
The earthing symbol at masts does not indicate that each mast needs an additional earthing electrode.
NOTE 2
It is also possible to use a RCBO (IEC 60050-442-05-04) instead of circuit breaker in combination with RCCB.
7.4.4.2
D.C. railways
The running rails of d.c. railways are not connected to structure earth and earth. The running rails and the
MEB of the auxiliary power supply system are normally not connected directly for stray current reasons. For
equipment within the overhead contact line zone or within the current collector zone, the PE conductor shall
be able to carry the relevant traction fault current. Voltage limiting devices (VLD) shall provide a connection
between MEB and return circuit in case of an earth fault of the contact line system.
If such equipment is mounted on a mast a connection between the equipment and the return circuit via
VLD-F shall be installed.
The PE conductor shall not be connected to the exposed conductive parts of the equipment.
The exposed conductive parts may alternatively be connected to the PE conductor of the supply cable via an
appropriate device such as a capacitor. A discharge resistor shall be connected in parallel to the appropriate
device.
The dimensioning of the capacitor shall guarantee the tripping current to fulfil the permissible touch voltage.
NOTE 1
The appropriate device prevents traction return currents flowing via the protective conductor.
If electrical equipment of protection Class II is used (see 7.3.2) the provisions for parts of small dimension
may be applied.
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EN 50122-1:2011
Low voltage equipment mounted on traction power equipment or parts which is protected by a frame fault
protection device may not be connected to the PE conductor of low voltage supply cable. The device shall be
equipotentially bonded to the traction power equipment frame.
If work is carried out on vehicles, on running rails, or on conductive parts which are connected to the return
circuit, using protection Class I electrical equipment which is plugged into sockets supplied from the railway
network, these wall sockets shall be connected to the railway network by residual-current protective devices
or by transformers with separate windings. If residual-current protective devices are used, the protective
conductor shall be connected to PE conductor via an appropriate device such as a capacitor. A discharge
resistor shall be connected in parallel with a capacitor.
Overcurrent protective devices shall also be applied in the neutral conductor for electric circuits without RCD,
i.e. circuit breaker with two- or four-protected poles according to EN 60898-1. In case of a tripping, all
conductors shall be switched-off simultaneously. Fuses shall not be used.
Figure 22 shows the provisions for a TT system and Figure 23 for a TN system applied in a d.c. railway
system.
In workshops and similar locations where the running rails are insulated from the main line MEB and running
rails may be directly connected in order to reduce the effect of touch voltage.
1
2
L1
L2
L3
N
PE
5
RCCB
I >> I >> I >>
6 7 8
3
9
RCCB
M
11
12
4
10
10
10
Key
1
electricity supply network
7
heating
2
railway network
8
lightning protection
3
public earth
9
railway structure earth
4
overhead contact line and current collector zone
10
VLD
5
MEB
11
1st insulation
6
water and gas pipes
12
2nd insulation (only for LV traction systems)
Figure 22 — TT system for d.c. railways
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EN 50122-1:2011
1
– 52 –
2
L1
L2
L3
N
PE
5
RCCB
I >> I >> I >>
6 7 8
3
9
RCCB
M
11
12
4
10
10
10
Key
1
electricity supply network
7
heating
2
railway network
8
lightning protection
3
public earth
9
railway structure earth
4
overhead contact line and current collector zone
10
VLD
5
MEB
11
1st insulation
6
water and gas pipes
12
2nd insulation (only for LV traction systems)
Figure 23 — TN system for d.c. railways
NOTE 2
The earthing symbol at masts does not indicate that each mast needs an additional earthing electrode.
NOTE 3
It is also possible to use a RCBO (IEC 60050-442-05-04) instead of circuit breaker in combination with RCCB.
8
8.1
Protective provisions where track systems, which are utilized for carrying
traction return current, or/and contact line systems pass through hazardous
zones
General
The requirements given in 8.2 to 8.6 shall apply to installations where protective provisions against explosion
due to sparking are prescribed by other standards if a dangerous inductive, conductive or capacitive
influence from the railway cannot be excluded.
NOTE 1
Hazardous zones are defined in national safety regulations.
NOTE 2
Explosion due to sparking may, for example, result from:
–
contact with an contact line;
–
rupture of a contact wire;
–
voltage between running rails utilized for carrying traction return current and earth (rail potential);
–
discharge of static electricity to the return circuit;
–
disconnecting of a conductive part carrying a part of the return current.
NOTE 3
Examples of such installations are loading installations or parts of refineries or chemical firms or tank depots.
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8.2
EN 50122-1:2011
Equipotential bonding
Each charging nozzle shall be connected directly to the return circuit.
Cross bonds shall be provided at intervals not exceeding 70 m between:
–
the rails of a track;
–
neighbouring tracks (see Figure 24).
Tracks and adjacent conductive installations shall be conductively interconnected.
2
4
4
7
3
11
11
11
70 m
5
6
1
9
8
10
Key
1
overhead contact line zone according to Figure 1
6
track-to-track cross bonds
2
border of the overhead contact line zone
7
charging nozzle
3
border of the hazardous zone
8
overhead contact line wiring diagram
4
connection to the return circuit and equipotential bonding
9
switch with contact to earth
5
rail-to-rail cross bonds
10
section insulators
11
return circuit (running rails)
Figure 24 — Disposition of rail-to-rail cross bonds and track-to-track cross bonds
(double-rail illustration) and connection of the contact line in case
of the loading siding having a contact line
8.3
Parallel pipework
A pipework carrying explosive liquids or gases shall not be used intentionally as a parallel return conductor.
A common pipework inside the contact line or pantograph zone feeding several charging nozzles shall be
insulated between each charging nozzle.
Each conductive part which is connected to the return circuit shall be insulated from earth. This applies both
to a.c. railways and to d.c. railways as well.
8.4
Insulating joints
Conductive pipework carrying explosive liquids or gases leaving the contact line or pantograph zone shall be
insulated outside of the contact line or pantograph zone (see Figure 24). The insulating joint shall withstand
the voltage of the contact line. If the voltage over the insulating joint is bridgeable by a person, the voltage
shall not exceed the limits given in Clause 9.
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EN 50122-1:2011
8.5
– 54 –
Surge arrester
If flashover or voltage breakdown of the insulating pieces is likely due to lightning strike, the insulating pieces
shall be bridged by means of surge arresters (see Figure 25). Surge arresters used in hazardous zones shall
be of flameproof design. Care shall be taken to ensure that accidental bridging of isolation pieces or surge
arresters (e.g. by tools) is prevented.
1
2
3
TOR
4
5
Key
1
overhead contact line zone according to Figure 1
2
charging nozzle
3
surge arrester
4
insulating piece
5
connection to the return circuit and equipotential bonding
TOR top of rail
Figure 25 — Location of a surge arrester outside the overhead contact line zone of a loading
siding if there is a possibility of flashovers of the insulating pieces through lightning strikes
8.6
Contact line of loading sidings
The contact line of the loading siding shall be interruptible and shall be connectable to the return circuit by a
means which ensures that the loading procedure is not initiated unless the contact line is connected with the
return circuit (see Figure 24).
9
Limits for touch voltage and protection against the danger of rail potential
9.1
9.1.1
General
Rail potential
The local and time-dependent rail potential is the main reason for touch voltages under operating and fault
conditions. The permissible touch voltage therefore is subdivided in long-term values for operation and shortterm values for fault conditions including specific short-term operational situations.
For voltages which vary significantly, particular care shall be given to the choice of the time interval so as to
ensure that the most unfavourable condition has been considered.
NOTE
The values given in the tables of Clause 9 are based on the assumption, that the current path through the human body is
from hand to both feet. This includes the current path hand to hand, see Annex D. For maintenance purposes it can be necessary to
consider more dangerous currents paths through the human body. Additional protective provisions can then be necessary.
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9.1.2
EN 50122-1:2011
Body voltage and touch voltage
The values for the touch voltage and body voltage given in Clause 9 shall be the maximum values
considered acceptable. All voltages (including d.c. voltages) given in Clause 9 are r.m.s. values, over the
considered interval in accordance with IEC 60050-101-14-15.
The resistance of the standing surface, according to HD 637 S1, may be taken into account additionally at
any time interval.
NOTE 1
The calculation methods for the values in the following tables are shown in Annex D.
NOTE 2
Measurement methods for effective/prospective touch voltages are given in Annex E.
NOTE 3
For all tables of Clause 9 the values for intermediate durations may be calculated by linear interpolation.
9.1.3
Touch voltage at vehicles
Attention is directed to the problem that can occur, if a vehicle is touched in case of a fault to or in the
vehicle. The voltage acting as the source voltage in the touching circuit is caused by the voltage drop over
the vehicle impedance to the running rail and the whole or a part of the rail potential. For impedance values
between the vehicle body and rail see EN 50153:2002, 6.4.3. According to EN 50153:2002, 6.4.4 the voltage
drop over the vehicle including the relevant part of the rail potential shall not exceed the values given in
Clause 9.
NOTE
If the fault current is unknown, short-circuit currents according to EN 50388:2008, Table 7 may be used for worst case
calculations.
9.1.4
Fault duration condition
For the evaluation of the relevant fault duration in order to assess the permissible touch voltage, the correct
operation of the protection devices and switches shall be assumed. Multiple simultaneously occurring faults
do not need to be considered.
9.1.5
Voltage limits and time duration aspects
For any moment in time and any time interval at that moment, the maximum r.m.s voltage value over the
time interval shall not surpass the voltage given for the applicable time interval as specified in Table 3 and
Table 4 for a.c. systems and in Table 5 and Table 6 for d.c. systems.
NOTE Long-term conditions are associated with operation conditions and short-term conditions are associated with fault conditions or
for example switching operations.
9.2
9.2.1
A.C. traction systems
General
In order to determine whether an impermissible high touch voltage can occur, the rail potential at the relevant
point shall be evaluated both for operation and for fault conditions.
If the rail potential is determined by calculation, such calculation shall employ the maximum operating current
and short-circuit current and also the initial short-circuit current.
NOTE
Guiding values for the normalized rail potential gradient can be found in C.1.
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EN 50122-1:2011
9.2.2
9.2.2.1
– 56 –
A.C. voltage limits for the safety of persons
Basic values of the body voltage Ub
The body voltages Ub shall not exceed the values shown in Table 3 for the corresponding time durations.
Table 3 — Maximum permissible body voltages Ub, max in a.c. traction systems
as a function of time duration
Key
t
Ub, max
9.2.2.2
t
Ub, max
s
V
> 300
60
300
65
1
75
0,9
80
0,8
85
0,7
90
0,6
100
0,5
120
0,4
150
0,3
230
0,2
295
0,1
345
0,05
360
0,02
370
time duration
permissible body voltage
Effective touch voltage limits
For long-term conditions t # 0,7 s, the effective touch voltage shall not exceed the values shown in Table 4.
For short-term conditions, t < 0,7 s, the permissible body voltages are considered to be complied with, if the
values for the effective touch voltage in Table 4 are not exceeded.
NOTE
An additional resistance of 1 000 ! for old wet shoes is included in the values, see D.1.
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EN 50122-1:2011
Table 4 — Maximum permissible effective touch voltages Ute, max
in a.c. traction systems as a function of time duration
Ute, max
Ute, max
long-term
short-term
V
V
> 300
60
-
300
65
-
1
75
-
0,9
80
-
0,8
85
-
0,7
90
-
< 0,7
-
155
0,6
-
180
0,5
-
220
0,4
-
295
0,3
-
480
0,2
-
645
0,1
-
785
0,05
-
835
0,02
-
865
t
s
Key
t
time duration
Ute, max permissible effective touch voltage
Residual touch voltages caused by different tripping times shall be switched off within the corresponding
duration time according to Table 4.
NOTE
9.2.2.3
Different tripping times are caused for example by relay coordination, different types of relays and different opening times.
Workshops and similar locations
In workshops and similar locations the effective touch voltage shall not exceed the 25 V limit of let go. For
short-term conditions 9.2.2.2 shall apply.
NOTE
The reduced level for touch voltages in workshops has been chosen considering the high risk of injury for persons due to
uncontrolled reactions caused by touch voltages during work. Injuries through the direct effect of electrical voltage and current are not
expected on this level.
9.2.2.4
Measures to reduce the risks from touch voltages
If the limits given in 9.2.2.2 or in 9.2.2.3 are exceeded, the following provisions with help of Figure 26 shall be
considered to reduce the risks from touch voltages directly, or by means of a rail potential reduction, or by
management.
The following list contains some examples of measures:
–
reduction of the rail to earth resistance, e.g. by means of improved or additional earth electrodes;
–
equipotential bonding;
–
improvement of the return circuit taking electromagnetic coupling into account;
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EN 50122-1:2011
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–
insulation of the standing surface;
–
potential grading by means of appropriate surface earth electrodes;
–
obstacles or insulated accessible parts;
–
access restrictions (fences) including instructions for maintenance staff;
–
reduction of fault and/or operation currents;
–
voltage-limiting device;
–
reduction of the tripping time needed to interrupt the short-circuit current.
start
basic design
yes
URE < Ute, max
suitable measures
according to 9.2.2.4
no
yes
transferred
potentials
URE < a Ute, max
no
yes
URE < b Ute, max
no
Ute < Ute, max
no
or
no
yes
yes
suitable measures
according to 9.2.2.4
correct
design
Key
URE
rail potential
Ute
effective touch voltage
Ute, max permissible effective touch voltage
a=2
factor for 50 % potential decrease, according to Figure 9.2 in HD 637 S1:1999, see Figure C.1
b = 3,3
factor for 30 % potential decrease, see Figure C.2
Figure 26 — Design of return circuit, with regard to permissible effective touch voltage by
checking the rail potential or the effective touch voltage
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9.3
EN 50122-1:2011
D.C. traction systems
9.3.1
General
In order to determine whether an impermissible high touch voltage can occur, the rail potential at the relevant
point shall be evaluated both for normal operation and for fault conditions on the basis of the voltage drop in
the return circuit.
If the rail potential is determined by calculation, such calculation shall employ the maximum operating current
flowing in the running rails. For short-circuits the maximum current during the disconnection time of the fault
shall be taken into account (see also C.2).
9.3.2
9.3.2.1
D.C. voltage limits for the safety of persons
Basic values of the body voltage
Table 5 — Maximum permissible body voltages Ub, max in d.c. traction systems
as a function of time duration
t
Ub, max
s
V
> 300
120
300
150
1
160
0,9
165
0,8
170
0,7
175
0,6
180
0,5
190
0,4
205
0,3
220
0,2
245
0,1
285
0,05
325
0,02
370
Key
t
Ub, max
9.3.2.2
time duration
permissible body voltage
Effective touch voltage limits
For long-term conditions t # 0,7 s the effective touch voltage shall not exceed the values for the body voltage
shown in Table 6.
For short-term conditions, t < 0,7 s, the body voltages are considered to be satisfied, if the values for the
effective touch voltage in Table 6 are not exceed.
NOTE
An additional resistance of 1 000 ! for old wet shoes is included in the values, see D.1.
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EN 50122-1:2011
– 60 –
Table 6 — Maximum permissible effective touch voltages Ute, max in d.c. traction systems
as a function of time duration
t
Ute, max
Ute, max
long-term
short-term
V
V
> 300
120
-
300
150
-
1
160
-
0,9
165
-
0,8
170
-
0,7
175
-
< 0,7
-
350
0,6
-
360
0,5
-
385
0,4
-
420
0,3
-
460
0,2
-
520
0,1
-
625
0,05
-
735
0,02
-
870
s
Key
t
time duration
Ute, max permissible effective touch voltage
9.3.2.3
Workshops and similar locations
In workshops and similar locations the effective touch voltage shall not exceed 60 V. For short-term
conditions 9.3.2.2 shall apply.
NOTE
The reduced level for touch voltages in workshops has been chosen considering the high risk of injury for persons due to
uncontrolled reactions caused by touch voltages during work. Injuries through the direct effect of electrical voltage and current are not
expected on this level.
9.3.2.4
Measures to reduce the risks from touch voltages
If the limits given in 9.3.2.2 or 9.3.2.3 are exceeded, the following provisions shall be considered to reduce
the risks from touch voltages directly, or by means of a rail potential reduction, or by management. The
following list contains some examples:
–
reduced length of feeding section;
–
increasing of conductance of the return circuit;
–
insulation of the standing surface;
–
reduction of the tripping time needed to interrupt the short-circuit current;
–
voltage-limiting device.
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EN 50122-1:2011
10 Additional protective provisions
10.1 Traction substations and traction switching stations
Substations and switching stations shall conform to HD 637 S1 for all matters concerning electrical safety
and earthing. This shall apply also with respect to the presence of a.c. or d.c. electric systems relating to
electrical traction, with the following additional requirements:
–
the effective touch voltages caused by the traction system shall not exceed values given in 9.2.2 and
9.3.2;
–
in a.c. traction systems a direct connection shall be made between the return circuit and the earthing
system of the substation or the switching station;
–
in d.c. traction systems connections between return circuit and earthing system of the substation shall
be designed in accordance with EN 50122–2, except where safety considerations require direct earthing
(e.g. workshops and depots);
–
for insulation co-ordination of equipment connected to the contact line system, EN 50124-1 shall apply;
–
switchgear shall have sufficient performance to clear any fault current on the contact line system.
10.2 Cables
10.2.1 General requirements
Multiple connection of metallic sheaths, armour or shields of power cables to the return circuit is permissible
only where an impermissible temperature rise cannot occur as a result of such connections. If multiple
connection of metallic sheaths, armour or shields of power cable to the return circuit is necessary, it shall be
ensured that the metallic sheaths, armour or shields of power cables do not carry impermissible high traction
return currents.
10.2.2 Cables in a.c. traction power supply systems
The metallic sheaths, armour or shields of single-phase a.c. feeder cables shall be connected to the return
circuit. Where necessary, special provisions shall be adopted to ensure that an impermissible temperature
rise does not occur in the metallic sheaths, armour or shields due to induction with the supply current as a
result of earthing at both ends or an impermissible high voltage as a result of earthing at one end only.
10.2.3 Cables in d.c. traction power supply systems
The metallic sheaths, armour or shields of d.c. feeder cables shall be insulated with respect to earth if they
are connected to the return circuit. If any metallic sheaths, armour or shields of d.c. feeder cables are not
insulated with respect to earth, then measures shall be applied, to protect persons against impermissible
high touch voltages. Measures shall be applied, to avoid excessive heating of the metallic sheaths, armour or
shields of d.c. feeder cables by the current which flows in them.
10.3 Return circuit connections and earthing conductors
10.3.1 General requirements
The return current busbar of the substation shall be connected to the running rails, return conductors or
return conductor rails by at least two return cables, either directly or via the midpoint of impedance bonds.
The return cables shall be sufficient for the maximum load current. The number of connecting cables to the
running rails shall take into account that one cable connection can be interrupted. The return circuit shall not
include fuses, non lockable switches and joint straps which can be released without a tool.
All conductors shall be designed in such a way that they satisfy the thermal loads which can be produced by
the traction return current as well in normal operations and during short-circuits. For mechanical reasons
conductors directly connected to rails shall have a minimum cross-section of 50 mm². For d.c. railways
insulated conductors shall be used.
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EN 50122-1:2011
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All earthing conductors and earthing electrodes, which are not connected to and not a part of the return
circuit, shall be designed and constructed as required in HD 637 S1. This applies in particular to materials
choice and to dimensioning, in consideration of mechanical strength, and thermal effects and corrosion.
In d.c. traction systems the thermal dimensioning of such conductors shall be based on the value of the
expected prospective short-circuit current and the maximum time to clear it at the location.
Whenever a switching device is installed in the track return system, another switch shall be installed in the
supply circuit, and the switching device shall be interlocked so that it cannot be opened before the supply
switch is open. For trolleybuses see 5.6.3.2. For railway systems in which the traction current is confined
within conductors insulated with respect to earth the same solution shall be used.
For d.c. railways see also EN 50122-2.
10.3.2 Continuity of the return circuit
Rail joints in running rails used for carrying traction return current shall be provided with rail joint bonds. This
also applies to the components of crossings and points. In the case of high voltage a.c. traction systems, the
tight joint fish-plates generally provide an adequate conducting bridge.
In the case of track circuits for which rail joint bonds are impossible for technical reasons, the traction return
current shall, where necessary, be returned by means of impedance bonds.
At interruptions in tracks, for example at movable bridges or track weighbridges, conductors shall be
arranged so as to ensure that the return circuit is continuous.
10.3.3 Cross bonding of the return circuit
Track-to-track cross bonding shall be provided at suitable intervals in order to ensure the continuity of the
traction return current path and the proper distribution of the traction return currents, so that the touch
voltages will not exceed the permissible levels, under both operating and fault conditions.
The specific arrangements for connections of track-to-track cross bonding shall take account of the trackcircuiting arrangements in use and the overall traction power supply system design.
In areas without track circuits only, the running rails of each track shall be connected by rail-to-rail cross
bonds, as required for electrical safety.
NOTE
Steel sleepers or riveted or screwed rail tie bars between the running rails provide sufficient transverse connection if the
running rails are fixed to them without any intermediate insulating layers.
10.3.4 Railway systems in which the traction current is confined within insulated conductors
If the running rails are not used by the traction return current in normal operation, at least one running rail of
each track shall nevertheless be electrically continuous as in 10.3.1 to 10.3.3 in order to simplify the
detection and localisation of earth faults on the contact lines.
10.4 Removing of decommissioned overhead contact lines
For a track which is permanently decommissioned, the overhead contact line and associated feeders shall
be removed.
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EN 50122-1:2011
10.5 Means of achieving safe isolation between sections
10.5.1 Section insulators
If section insulators are used as isolating gaps in overhead contact lines to isolate feeding sections, the
minimum clearance in air may be reduced compared with the requirements given in EN 50119 and
EN 50124-1. A smaller clearance than the normal minimum clearance in air is allowable. The reduced
clearances shall not be less than the dynamic electrical clearance defined in EN 50119.
NOTE
Section insulators which are inserted in the contact wires have contact with the current collector. Therefore their mechanical
design should comply with the current collection requirements of EN 50119. These requirements impose limits concerning the possible
clearances between different live parts, between live parts and earthed parts and the size and the weight. Because of that, it is
necessary to allow these smaller distances.
10.5.2 Isolating gaps
Isolating gaps between overhead contact line sections may be bridged by insulators without provisions
against leakage currents if regulations impose that maintenance work shall be performed only on overhead
contact line sections which are connected to the return circuit (running rails).
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EN 50122-1:2011
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Annex A
(informative)
Typical obstacles
Dimensions in metres
5
1,0
1 ,4
5
a
4
20°
0,5
1,45
a
1,45
10
7
a
a
9
8
6
0,5
a)
1,45
a
1,45
8
a
10
7
11
b)
1,0
1,0
1,5
1,8
1,0
c)
1
2
3
Key
1
solid-wall design or obstacle conforming to degree of
protection IP3X as defined in EN 60529
2
mesh screen with a maximum 1 200 mm² mesh size (can
also be solid-wall design)
3
railing, mesh construction (can also be solid-wall design)
4
side view
5
front view
6
plan view
7
contact wire catenary line Feeder
8
pantograph
9
contact wire
10
line feeder
11
half pantograph zone
a
the dimension is taken from Figure 3
Figure A.1 — Examples of obstacles along the sides of standing surfaces in public areas for
protection against direct contact when above live parts on the outside of vehicles or live parts
of an overhead contact line system for low voltages (see 5.3.2.2)
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EN 50122-1:2011
Dimensions in metres
5
2,
25
1,0
a
4
20°
2,25
1,5
a
2,25
a
10
7
9
8
6
0,5
a)
2,25
a
a
2,25
10
8
7
11
b)
1,0
1,0
1,5
1,8
1,0
c)
1
2
3
Key
1
solid-wall design or obstacle conforming to degree of
protection IP3X as defined in EN 60529
2
mesh screen with a maximum 1 200 mm² mesh size (can
also be solid-wall design)
3
railing, mesh construction (can also be solid-wall design)
4
side view
5
front view
6
plan view
7
contact wire catenary line Feeder
8
pantograph
9
contact wire
10
line feeder
11
half pantograph zone
a
the dimension is taken from Figure 3
Figure A.2 — Examples of obstacles along the sides of standing surfaces in public areas for
protection against direct contact when above live parts on the outside of vehicles or live parts
of an overhead contact line system for high voltages (see 5.3.2.2)
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EN 50122-1:2011
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Annex B
(normative)
Warning sign
Figure B.1 shows the warning sign, the broken arrow, as given in ISO 3864-1:2002 and
ISO 7010:2003 + A1:2006, which means "Caution, risk of electric shock".
2
1
Key
1
2
reflective yellow
black
Figure B.1 — Warning sign
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EN 50122-1:2011
Annex C
(informative)
Guiding values for rail potential gradient
C.1
A.C. traction systems
The value at which the rail potential for a.c. traction systems, given in 9.2 can act as a touch voltage should
be investigated. Guiding values for the rail potential gradient measured at right angle away from the track of
a.c. traction systems, where the running rails are directly earthed, are given in Figure C.1 and Table C.1 for
homogenous soil resistivity.
U RE
M
U RP
M
U PE
> 100 m
%
100
URP
UPE/URE x 100
URP/URE x 100
80
60
40
UPE
20
0
0
R
5
10
15
20
25
m
P
E
a
Key
a
E
M
P
R
URE
URP
UPE
30
distance between running rail (mast) and measuring point
earth
measuring electrode
measuring point
rail
rail potential
voltage between running rail (mast) and measuring point
voltage between measuring point and earth
Figure C.1 — Guidance values for the rail potential gradient measured
at the mast in a right angle to the track in an a.c. traction system
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EN 50122-1:2011
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Table C.1 — Guidance values for the rail potential gradient (see Figure C.1)
a
UPE/URE × 100
URP/URE × 100
m
%
%
1
70
30
2
50
50
5
30
70
10
20
80
20
10
90
50
5
95
100
0
100
Key
a
URE
URP
UPE
C.2
distance between running rail (mast) and measuring point
rail potential
voltage between running rail (mast) and measuring point
voltage between measuring point and earth
D.C. traction systems
Due to the fact that running rails are insulated with respect to soil, the rail voltage gradient can be very steep.
Therefore the whole rail potential can act as a touch voltage.
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EN 50122-1:2011
Annex D
(informative)
Effective touch voltage and body voltage with respect to the body current
D.1
Preconditions for the calculation
All voltages and currents in Annex D are r.m.s. values in accordance with IEC 60050-101-14-15.
The calculation of the values for the permissible effective touch voltage and body voltage in 9.2 and 9.3 are
based on:
–
IEC/TS 60479-1:2005;
–
HD 637 S1.
Following assumptions are made:
–
current path: one hand to both feet;
–
body impedance for large surface areas of contact in dry conditions;
–
50 % probability of body impedance higher than assumed value;
–
0 % probability of ventricular fibrillation (see IEC/TS 60479-1:2005, curve c1);
–
additional resistance Ra = 1 000 ! for old wet shoes for short-term conditions.
NOTE
Proceeding on the assumption that in most cases there is an additional resistance to the total body resistance because of
shoes and moreover that the probability of danger is very small within time intervals of less than 1 s, an additional resistance of 1 000 !,
to the values of Uc1 (curve c1) is taken into account for the calculation of the effective touch voltage for short-term conditions. This value
of old wet shoes corresponds to HD 637 S1.
The resistance of the standing surface, according to HD 637 S1, may be taken into account additionally at any time interval.
Regarding the risk of heart fibrillation the current path hand to hand is less restrictive than the current path
hand to feet, even when an additional resistance of 1 000 ! is included for old wet shoes.
For the limit of let go in workshops hand to hand is the more restrictive current path considering the presence
of shoes for employees (workers at site).
D.2
D.2.1
Impedances
Body impedance for a.c. and d.c. voltages
The total human body impedance at 50 % probability is indicated in IEC/TS 60479-1:2005, Table 1, relating
hand to hand current path. By applying the reduction factor r = 0,75 (IEC/TS 60479-1:2005, Figure 3) for the
hand to feet current path, Table D.1 is obtained.
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EN 50122-1:2011
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Table D.1 — Body impedance Zb and body current Ib
a.c. system
d.c. system
r = 0,75
r = 0,75
Ub
Zb(100)
Zb(75)
Ib(75)
Rb(100)
Rb(75)
Ib(75)
V
!
!
mA
!
!
mA
25
3 250
2 438
10
3 875
2 906
9
50
2 500
1 875
27
2 900
2 175
23
75
2 000
1 500
50
2 275
1 706
44
100
1 725
1 294
77
1 900
1 425
70
125
1 550
1 163
108
1 675
1 256
100
150
1 400
1 050
143
1 475
1 106
136
175
1 325
994
176
1 350
1 013
173
200
1 275
956
209
1 275
956
209
225
1 225
919
245
1 225
919
245
400
950
713
561
950
713
561
500
850
638
784
850
638
784
700
775
581
1 204
775
581
1 204
1 000
775
581
1 720
775
581
1 720
Key
3
Ib(75) = Ub/Zb(75) × 10 or Ib(75) = Ub/Rb(75) × 10
Ub
body voltage
Ib(75)
body current relating to Zb(75)
Zb(100)
total body impedance
Zb(75)
75 % of the total body impedance
Rb(100)
total body resistance
Rb(75)
75 % of the total body resistance
r
reduction factor
3
body current in milliamperes
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
– 71 –
D.2.2
EN 50122-1:2011
Additional resistances
Taking into account additional resistances, leads to Figure D.1.
Ib
Ub
Zb
Ute
Ra1
Us = Utp
1
Ra
Ra2
2
Key
1 standing surface
2 earth
Us source voltage
Utp prospective touch voltage
Ute effective touch voltage
Ub body voltage
Ib body current
Zb total body impedance
Ra1 additional resistance for shoes
Ra2 additional resistance of standing surface
Ra2 = ρs × 1,5 m
-1
ρs soil resistivity at the standing surface in ohm metres (!m)
Utp, max(t) = Ute, max(t) + Ib(t) × Ra2
Figure D.1 ! Equivalent circuit for the calculation of the permissible touch voltage
In case of a.c. railway lines, Utp corresponds to URP of Figure C.1.
Table D.2 provides an example for Ra2 = 150 ! of the standing surface and Ra1 = 1 000 ! for old wet shoes
and short-term conditions.
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EN 50122-1:2011
– 72 –
Table D.2 — Example of the maximum permissible prospective touch voltage for a.c. railways
for short-term conditions and Ra = 1 150 "
t
Utp, max
s
V
0,7
165
0,6
190
0,5
235
0,4
320
0,3
520
0,2
695
0,1
850
0,05
905
0,02
940
Key
t
Utp, max
D.3
time duration
maximum permissible prospective touch voltage
Body current and related body voltage
D.3.1
General
The values in Table D.3 and Table D.4 are based on:
–
current versus time curve c1 shown in IEC/TS 60479-1:2005;
–
body voltage Ub = f(Ib) obtained from the values in Table D.1.
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
– 73 –
D.3.2
EN 50122-1:2011
A.C. traction systems
Table D.3 — Body currents, body voltages and touch voltages as function
of time duration in a.c. traction systems
t
s
Ub, max
Uc1
Ic1
mA
V
V
Ute, max
Ute, max
long-term
short-term
V
V
> 300
37
62
60
60
-
300
38
64
65
65
-
1,0
50
75
75
75
-
0,9
52
77
80
80
-
0,8
58
83
85
85
-
0,7
66
91
90
90
-
< 0,7
66
91
90
-
155
0,6
78
101
100
-
180
0,5
100
119
120
-
220
0,4
145
152
155
-
295
0,3
252
230
230
-
480
0,2
350
293
295
-
645
0,1
440
343
345
-
785
0,05
475
361
360
-
835
0,02
495
370
370
-
865
NOTE
Columns t and Ic1 are applied from IEC/TS 60479-1. Column Uc1 is a result of iterative calculations with column Ic1 and
Table D.1. Column Ub, max is gained by good experience and differs slightly from the calculated ones from Uc1. Column Ute, max shortterm indicates the relevant touch voltages for short-term conditions considering an additional resistance for old wet shoes. Column
Ute, max long-term indicates the relevant touch voltages for long-term conditions.
Key
-3
Ute, max = Uc1 + Ra1 × Ic1 × 10 (short-term)
t
time duration of current flow
Ic1
body current which corresponds to curve c1 in IEC/TS 60479-1:2005
Ra1
resistance for old wet shoes (Ra1 = 1 000 !)
Uc1
body voltage, corresponds to Ic1
Ub, max
maximum body voltage
Ute, max
maximum permissible effective touch voltage
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
EN 50122-1:2011
D.3.3
– 74 –
D.C. traction systems
Table D.4 — Body currents, body voltages and touch voltages as function
of time duration in d.c. traction systems
Ic1
t
s
mA
Uc1
V
Ub, max
V
Ute, max
Ute, max
long-term
short-term
V
V
> 300
140
153
120
120
-
300
140
153
150
150
-
1,0
150
160
160
160
-
0,9
160
167
165
165
-
0,8
165
170
170
170
-
0,7
175
177
175
175
-
< 0,7
175
177
175
-
350
0,6
180
180
180
-
360
0,5
195
191
190
-
385
0,4
215
204
205
-
420
0,3
240
222
220
-
460
0,2
275
246
245
-
520
0,1
340
287
285
-
625
0,05
410
327
325
-
735
0,02
500
372
370
-
870
NOTE
Columns t and Ic1 are applied from IEC/TS 60479-1. Column Uc1 is a result of iterative calculations with column Ic1 and
Table D.1. Column Ub, max is gained by good experience and differs slightly from the calculated ones from Uc1. Column Ute, max shortterm indicates the relevant touch voltages for short-term conditions considering an additional resistance for old wet shoes. Column
Ute, max long-term indicates the relevant touch voltages for long-term conditions.
Key
-3
Ute, max = Uc1 + Ra1 × Ic1 × 10 (short-term)
t
time duration of current flow
Ic1
body current which corresponds to curve c1 in IEC/TS 60479-1:2005
Ra1
resistance for old wet shoes (Ra1 = 1 000 !)
Uc1
body voltage, corresponds to Ic1
Ute, max
permissible effective touch voltage
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
– 75 –
EN 50122-1:2011
Annex E
(normative)
Measurement methods for effective touch voltages
The measurement of the effective touch voltage shall be carried out as follows:
The effective touch voltage shall be measured over a resistance which corresponds to the human body
resistance Zb and to the additional resistance Ra1, see Figure D.1. It shall be at least:
–
Zb + Ra1 = 1 000 ! + 1 000 ! = 2 000 ! for short-term conditions;
–
Zb + Ra1 = 2 200 ! + 0 ! = 2 200 ! for long-term conditions;
NOTE 1
For practical applications a value of 2 200 ! may be used for all conditions.
The measuring electrode, for the simulation of feet, shall have a total area of 400 cm² and shall be pressed
to the earth with a minimum force of 500 N. Alternatively, a measuring electrode with 2 cm diameter and
30 cm length may be used. This corresponds to an earth electrode with 2,2 !/!m .
To measure the effective touch voltage for concrete or dried up soil a wet cloth or water film shall be placed
between the foot electrodes and earth. The foot electrodes shall be placed at a distance not less than 1 m
from the exposed conductive part.
A measuring electrode, e.g. a tip electrode, shall be used for simulation of a hand. In this case paint coatings
(but not insulation) shall be pierced reliably.
One clamp of the voltmeter shall be connected to the hand-electrode, the other clamp shall be connected to
the feet electrode. It is sufficient to carry out such measurements by random checks of an installation.
NOTE 2
The effective touch voltage is always lower than the prospective touch voltage. Therefore a simple assessment is possible
by using a simple measurement of the prospective touch voltage by a voltmeter with a high internal resistance and an appropriate earth
electrode.
At measuring points where the resistance to earth of the measuring electrode for the simulation of feet does not exceed several hundred
ohms, a measurement with and without parallel resistance is recommended. The resistance represents the human body resistance Zb
and to the additional resistance Ra1. If the voltage breaks down when using the parallel resistance, it can be concluded that effective
touch voltage is considerably lower than the prospective touch voltage, e.g. the rail potential.
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
EN 50122-1:2011
– 76 –
Annex F
(normative)
The use of voltage-limiting devices
F.1
General
A voltage-limiting device (VLD) has a high resistance when the applied voltage is less than a specified level
and becomes conductive, when the specified level is exceeded. It can remain as non permanent or
permanent connection when the voltage decreases below the specified value.
F.2
Types
VLDs protect against impermissible touch voltages in case of faults and in case of operation. The
requirements are fulfilled by VLD-F or VLD-O types, where also one device can fulfill both requirements.
Type 1 (VLD-F):
–
For the case of a fault with a connection between a live part of the traction power supply system and a
conductive part not intentionally bonded to the return circuit, the VLD-F protects against an
impermissible touch voltage by becoming conductive and causing tripping of the power supply. The
VLD-F is normally connected between the part to be protected and the return circuit.
NOTE
This includes:
–
objects in overhead contact line zone or current collector zone, which can be hit by wire or dewired current collector;
–
mast, which can become live due to insulation failure.
Type 2 (VLD-O):
–
The VLD-O protects against impermissible voltage caused by rail potential in case of Operation and
short-circuits. In case of short-circuits the current path is identical to the operational one. The VLD-O
acts as an equipotential bonding device and thus limits the possible touch voltage. Only a part of the
return current flows through it. The permissible touch voltage according to 9.2 and 9.3 shall not be
exceeded. Tripping of the line circuit breakers caused by the VLD-O is not intended. The VLD-O is
normally connected between the return circuit and structure earth, e.g. in passenger stations or
substations.
F.3
Technical requirements
Each VLD shall be able to conduct the levels of current which will flow in it.
A VLD shall not open unless the levels of current flowing in it are lower than the levels which the device can
interrupt safely.
The VLD shall be reset automatically or renewed before significant damage like e.g. stray current corrosion
is caused by the current which flows through it.
If the VLD has operated and is not reset automatically a procedure or systems shall be put in place to note
and rectify the cause of such event rapidly.
NOTE 1
For some kinds of systems a closed VLD can be reset automatically after a defined time considering acceleration times and
auto reclose cycles of protection.
NOTE 2
A guide value for the maximum reset time of VLD-O is 60 s, which may be adapted on the typical traffic circumstances.
If maintenance for VLDs is required, then their electrical connections shall be arranged so that it is possible
to bypass the VLD in order to protect the workers against hazards of touch voltages or arcing.
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
– 77 –
EN 50122-1:2011
Annex G
(normative)
Special national conditions
Special national condition: National characteristic or practice which cannot be changed even over a long
period, e.g. climatic conditions, electrical earthing conditions. If it affects harmonization, it forms part of this
European Standard or Harmonization Document.
For the countries in which the relevant special national conditions apply these provisions are normative, for
other countries they are informative.
Clause
Special National Conditions
4.1
Denmark
In Denmark the parameters X, Y and Z, which define the dimensions of the overhead
contact line and current collector zones according to 4.1, Figure 1, are set to be the
following:
- X = 5,0 m;
- Y = 2,5 m;
- Z = 2,5 m.
Furthermore, the overhead contact line zone is expanded at platforms, workshops and
similar locations as shown in the figure below.
LP
S1
Sel
S2
HP
S3
CCZ
Z
Sel
OCLZP
SH
TCL
Hmax
OCLZ
Y
Y
TOR
X
Key
OCLZP
X
overhead contact line zone at platforms, workshops and similar locations
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
EN 50122-1:2011
4.1
– 78 –
France
The overhead contact line and current collector zone according to 4.1, Figure 1 has to be
defined by the infrastructure owner.
In absence of such a definition the following values shall be applied:
- X = 4,0 m;
- Y = 2,0 m;
- Z = 2,0 m in the limit of SH = 8,0 m.
5.2.1
United Kingdom
The public area clearances shown in Figure 4 shall be replaced by the arrangements
shown in the figure below. In addition, in cases of special difficulty up to half the earthed
end of an insulator may extend over the standing surface, subject to a maximum horizontal
incursion of 300 mm. In this case the vertical position of the insulator shall be no lower
than the contact wire height at the location under consideration.
NOTE
The revised clearance is due to restricted infrastructure clearances. In order to comply with the public
area dimension in Figure 4 it would be necessary to change a large number of civil engineering structures, at a
very high cost.
Key
1
public areas
2
standing surface
3
contact wire height
4
support insulator incursion space
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
– 79 –
EN 50122-1:2011
Annex H
(normative)
A-deviations
Clause
4.1
Switzerland
In Switzerland the zones defined for protective provisions shown in Figure 1 shall be replaced
by the ones defined in the Regulation SR 734.42 (Directive on the Railway’s Electrical
Installations).
9.2
Switzerland
In Switzerland the maximum permissible touch voltage for a.c. railway systems given in Table 4
shall be replaced by the ones defined in the Regulation SR 734.2 (Directive on the Electrical
Power Installations) Articles 54 and 55.
9.3
Switzerland
In Switzerland the maximum permissible touch voltage for d.c. railway systems given in Table 6
shall be replaced by the ones defined in the Regulation SR 734.2 (Directive on the Electrical
Power Installations) Articles 54 and 55.
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
EN 50122-1:2011
– 80 –
Annex ZZ
(informative)
Coverage of Essential Requirements of EC Directives
This European Standard has been prepared under a mandate given to CENELEC by the European
Commission and the European Free Trade Association and within its scope the standard covers all relevant
essential requirements as given in Annex III of the EC Directive 96/48/EC (HSR), in Annex III of the EC
Directive 2001/16/EC (CONRAIL) and in Annex III of the EC Directive 2008/57/EC (RAIL).
Compliance with this standard provides one means of conformity with the specified essential requirements of
the Directive(s) concerned.
WARNING: Other requirements and other EC Directives may be applicable to the products falling within the
scope of this standard.
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
– 81 –
EN 50122-1:2011
Bibliography
EN 50122-3, Railway applications – Fixed installations – Electrical safety, earthing and the return circuit –
Part 3: Mutual interaction of a.c. and d.c. traction systems
EN 50388:2008, Railway applications – Power supply and rolling stock – Technical criteria for the
coordination between power supply (substation) and rolling stock to achieve interoperability
EN 60664-1:2007, Insulation coordination for equipment within low-voltage systems – Part 1: Principles,
requirements and tests (IEC 60664-1:2007)
EN 60721 (all parts), Classification of environmental conditions (IEC 60721 series)
EN 61219, Live working – Earthing or earthing and short-circuiting equipment using lances as short-circuiting
device – Lance earthing (IEC 61219)
EN 61558-2-6, Safety of transformers, reactors, power supply units and similar products for supply voltages
up to 1 100 V – Part 2-6: Particular requirements and tests for safety isolating transformers and power supply
units incorporating safety isolating transformers (IEC 61558-2-6)
IEC 60050-551, International Electrotechnical Vocabulary – Chapter 551: Power electronics
IEC 60364-1, Low-voltage electrical installations – Part 1: Fundamental principles, assessment of general
characteristics, definitions
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
Corrigendum to EN 50122-1:2011
English version
___________
Clause 5, Protective provisions against direct contact
In Fig. 7, add in the key list between d and x a new line and insert:
h
Height
a
In Fig. 8, add in the key list between d and a new line and insert:
h
Height
In Fig. 9, replace key 1 by:
1
Solid wall design
a
In Fig. 9, add in the key list between d and a new line and insert:
h
Height
a
In Fig. 10, add in the key list between d and a new line and insert:
h
Height
In Fig. 11, replace key 1 by:
1
Solid wall design
a
In Fig. 11, add in the key list between d and a new line and insert:
h
Height
__________
September 2012
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
EN 50122-1:2011/AC:2012
Corrigendum to EN 50122-1:2011
English version
___________
NOTE This corrigendum supersedes the corrigendum of September 2012.
Clause 5, Protective provisions against direct contact
In Fig. 7, add in the key list between d and x a new line and insert:
h
Height
a
In Fig. 8, add in the key list between d and a new line and insert:
h
Height
In Fig. 9, replace key 1 by:
1
Solid wall design
a
In Fig. 9, add in the key list between d and a new line and insert:
h
Height
a
In Fig. 10, add in the key list between d and a new line and insert:
h
Height
In Fig. 11, replace key 1 by:
1
Solid wall design
a
In Fig. 11, add in the key list between d and a new line and insert:
h
Height
Annex H
Delete the A-deviation 4.1 for Switzerland.
__________
November 2012
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
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Август 2011
ǩȂdzǫǨǸǹDzǰ ǹǺǨǵǬǨǸǺ
ǩȂdzǫǨǸǹDzǰ ǰǵǹǺǰǺǻǺ
ǯǨ ǹǺǨǵǬǨǸǺǰǯǨǾǰȇ
БДС EN 50122-1:2011/A1
ICS: 29.280
Железопътна техника. Стационарни инсталации. Електрическа
безопасност, заземяване и обратна верига. Част 1: Предписания
за защита срещу поражение от електрически ток
Европейският стандарт EN 50122-1:2011/A1:2011 има статут на български
стандарт от 2011-08-17.
Този стандарт е официалното издание на Българския институт за стандартизация на
английски език на европейския стандарт EN 50122-1:2011/A1:2011.
5 стр.
© ǩǰǹ 2011 ǩȢȓȋȈȘșȒȐȧȚ ȐȕșȚȐȚțȚ ȏȈ șȚȈȕȌȈȘȚȐȏȈȞȐȧ ȍ ȕȖșȐȚȍȓ ȕȈ
ȈȊȚȖȘșȒȐȚȍ ȗȘȈȊȈ. ǪșȧȒȖ ȊȢȏȗȘȖȐȏȊȍȎȌȈȕȍ, ȊȒȓȦȟȐȚȍȓȕȖ Ȑ ȟȈșȚȐȟȕȖ,
ȍ ȊȢȏȔȖȎȕȖ șȈȔȖ ș ȗȐșȔȍȕȖȚȖ ȘȈȏȘȍȠȍȕȐȍ ȕȈ ǩǰǹ, 1797 ǹȖȜȐȧ,
ȒȊ. ǰȏȋȘȍȊ, țȓ. “dzȢȟȍȏȈȘǹȚȈȕȟȍȊ” ȹ3
Национален № за позоваване:БДС EN
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
50122-1:2011/A1:2011
НАЦИОНАЛЕН ПРЕДГОВОР
Този стандарт е подготвен с участието на БИС/TK 70 "Железопътен транспорт".
Следват 3 страници на EN 50122-1:2011/A1:2011.
ǯȈ ȗȖȘȢȟȒȈ Ȑ ȏȈȒțȗțȊȈȕȍ ȕȈ șȚȈȕȌȈȘȚȐ, șȚȈȕȌȈȘȚȐȏȈȞȐȖȕȕȐ ȔȈȚȍȘȐȈȓȐ Ȑ șȗȍȞȐȈȓȐȏȐȘȈȕȐ ȐȏȌȈȕȐȧ ȕȈ
ǩǰǹ ȔȖȎȍ ȌȈ ȐȏȗȖȓȏȊȈȚȍ ȍȌȐȕ ȖȚ ȗȖșȖȟȍȕȐȚȍ ȕȈȟȐȕȐ:
-
Ǫ ȐȕȜȖȘȔȈȞȐȖȕȕȐȧ ȞȍȕȚȢȘ ȕȈ ǩǰǹ ȕȈ ȈȌȘȍș: ǹȖȜȐȧ, ȒȊ. ǰȏȋȘȍȊ, țȓ. ³dzȢȟȍȏȈȘǹȚȈȕȟȍȊ´ ȹ3, 1 ȍȚȈȎ
-
On-line ȕȈ ȕȈȠȈȚȈ ȐȕȚȍȘȕȍȚ șȚȘȈȕȐȞȈ: www.bds-bg.org
-
ǷȖ ȜȈȒș +359 2 873-55-97
-
ǷȖ ȍȓȍȒȚȘȖȕȕȈȚȈ ȗȖȡȈ: info@bds-bg.org
7KLVGRFXPHQWLVSHUVRQDOL]HGIRU^3XEOLF5HVRXUFH,QF`2UGHU ^`3XUFKDVHG ^`
EUROPEAN STANDARD
EN 50122-1/A1
NORME EUROPÉENNE
June 2011
EUROPÄISCHE NORM
ICS 29.280
English version
Railway applications Fixed installations Electrical safety, earthing and the return circuit Part 1: Protective provisions against electric shock
Applications ferroviaires Installations fixes Sécurité électrique, mise à la terre et
circuit de retour Partie 1: Mesures de protection contre les
chocs électriques
Bahnanwendungen Ortsfeste Anlagen Elektrische Sicherheit, Erdung und
Rückleitung Teil 1: Schutzmaßnahmen gegen
elektrischen Schlag
This amendment A1 modifies the European Standard EN 50122-1:2011; it was approved by CENELEC on
2011-04-25. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which
stipulate the conditions for giving this amendment the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This amendment exists in three official versions (English, French, German). A version in any other language
made by translation under the responsibility of a CENELEC member into its own language and notified to the
Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Management Centre: Avenue Marnix 17, B - 1000 Brussels
© 2011 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50122-1:2011/A1:2011 E
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EN 50122-1:2011/A1:2011
–2–
Foreword
This amendment to the European Standard EN 50122-1:2011 was prepared by SC 9XC, Electric
supply and earthing systems for public transport equipment and ancillary apparatus (Fixed
installations), of Technical Committee CENELEC TC 9X, Electrical and electronic applications for
railways.
The text of the draft was submitted to the Unique Acceptance Procedure and was approved by
CENELEC as Amendment A1 to EN 50122-1:2011 on 2011-04-25.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent
rights.
The following dates were fixed:
–
–
latest date by which the amendment has to be implemented
at national level by publication of an identical
national standard or by endorsement
latest date by which the national standards conflicting
with the amendment have to be withdrawn
(dop)
2012-04-25
(dow)
2014-04-25
__________
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–3–
EN 50122-1:2011/A1:2011
Text of A1 to EN 50122-1:2011
Clause 2, Normative references
Add "EN 50345, Railway applications – Fixed installations – Electric traction – Insulating synthetic
rope assemblies for support of overhead contact lines"
Clause 5, Protective provisions against direct contact
In 5.1, replace the last sentence by:
Exceptions are the parts of synthetic ropes which are further away from live parts than the creepage
length (according to EN 50345) with a minimum of 1 m.
Clause 6, Protective provisions against indirect contact and impermissible rail
potential
Replace the text of 6.2.1 by:
Except as noted below, exposed conductive parts of traction and non traction power supply which are
located within the contact line or the current collector zone shall be directly connected to the return
circuit.
NOTE 1 Connection to the running rails or to the return conductor is the preferred method to achieve this.
If it is determined that exposed conductive parts cannot be directly connected to the return circuit, then
appropriate alternative measures shall be adopted in order to prevent dangerous touch voltages.
NOTE 2 One possible solution is the use of a voltage-limiting device (minimum functionality VLD-F) to provide a
path for the current in the event of these exposed conductive parts becoming live.
In 6.3.1.1, add one new line at the end of NOTE 1:
–
running rails which are not connected to the return circuit e. g. used for track circuits.
In 6.3.1.2, replace the last paragraph by:
In case of an assembly of several small conductive parts the basic requirements in 6.3.1.1 are valid. In
particular, the assembly shall not be able to transfer dangerous potential from the fault location over a
distance exceeding the maximum dimensions given in Table 1.
Add the new subclause 6.3.1.5:
6.3.1.5 Protective provisions by means of bare conductive parts connected to the return circuit
The structure or equipment to be protected does not need to be connected to the return circuit if a
bare conductive part with appropriate design regarding position and current carrying capacity,
connected to the return circuit, is present between the structure to be protected and an overhead
contact line or a current collector. By this strategy a remaining dangerous touch voltage of the
structure is unlikely because of fault tripping. The bare conductive part shall be installed (or arranged)
inside of the overhead contact line zone and/or current collector zone.
NOTE The running rails fulfil this protective function for structures or equipment within 0,8 m on both sides of
the running rails and below. For d.c. railways this is applicable for open formation only.
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