Cables

The Distribution Systems Analysis Sub-Committee has been organizing Test Cases to provide benchmarks and challenging real cases for power systems analyses programs. The main focus of this test case is to calculate neutral to earth voltages - thus the acronym NEV Test Case - arising from unbalanced operation of transmission lines having neutral conductors, as well as on neutrals of

Cables (or wire ropes) made from NiTi shape memory alloy (SMA) wires are relatively new and unexplored structural elements that combine many of the advantages of conventional cables with the adaptive properties of SMAs (shape memory and superelasticity) and have a broad range of potential applications. In this two part series, an extensive set of uniaxial tension experiments was performed on two Nitinol cable constructions, a 7 Â 7 right regular lay and a 1 Â 27 alternating lay, to characterize their superelastic behavior in room temperature air. Details of the evolution of strain and temperature fields were captured by simultaneous stereo digital image correlation and infrared imaging, respectively. Here in Part I, the nearly isothermal, superelastic responses of the two cable designs are presented and compared. Overall, the 7 Â 7 construction has a mechanical response similar to that of straight wires with propagating transformation fronts and distinct stress plateaus during stress-induced transformations. The 1 Â 27 construction, however, exhibits a more compliant and stable mechanical response, trading a decreased force for additional elongation, and does not exhibit transformation fronts due to the deeper helix angles of the layers. In Part II that follows, selected subcomponents are dissected from the two cable's hierarchical constructions to experimentally break down the cable's responses.

In this paper, a numerical model of rectangular enclosure with apertures and a real receiving dipole antenna is considered for the purpose of accurate electric shielding effectiveness calculation. Dipole antenna is often used in practice to measure the level of electromagnetic field at some points inside the enclosure in order to estimate its shielding efficiency. Transmission-line matrix (TLM) method enhanced with compact wire model is applied here to generate the numerical model that takes into account the presence of receiving dipole antenna inside the enclosure. Using the proposed model, impact of receiving antenna on electric shielding effectiveness is illustrated on the example of enclosure with three different patterns of rectangular apertures and compared with the case when antenna presence is neglected. A plane wave propagating in a direction normal to the front wall of enclosure is assumed as an external interference signal.

This paper presents an investigation on the enhancement of electrical insulations of power cables materials using a new multi-nanoparticles technique. It has been studied the effect of adding specified types and concentrations of nanoparticles to polymeric materials such as PVC for controlling on electric and dielectric performance. Prediction of effective dielectric constant has been done for the new nanocomposites based on Interphase Power Law (IPL) model. The multi-nanoparticles technique has been succeeded for enhancing electric and dielectric performance of power cables insulation compared with adding individual nanoparticles. Finally, it has been investigated on electric field distribution in the new proposed modern insulations for three-phase core belted power cables. This research has focused on studying development of PVC nanocomposite materials performance with electric field distribution superior to the unfilled matrix, and has stressed particularly the effect of filler v...

... mechanism, this paper presents a precise comparison between the results obtained by an analytical model for a simple geometrically non-linear cable-stayed beam [12] and those obtained by both finite element analysis and experiments on a physical model. ...

Lightning surge is actually being considered as one of the most dangerous events in power distribution systems. Basically, it hits the overhead distribution line then propagates to the other network components, such as underground cables and transformers. Due to lightning strokes, insulation failure of such components could occur. The failure risk can be determined on the basis of network configuration, its parameters, and surge arresters data. The determination of this index can greatly help in optimizing the network surge protection. The implementation of an artificial neural network (ANN) for prediction of the failure risk for underground medium-voltage cables connected to overhead distribution lines is introduced. The main advantage of ANN actually is the time and effort savings due to the random nature of the problem and extended calculation process. The calculation of the failure risk using ANN is applied to a group of industrial surge arresters. The results of the ANN test coincide with the analytical ones.

Fibre optic sensor cable technology is relatively a new research area that combines a set of scientific and technical disciplines in order to meet distributed sensor system needs and quality standards. In this paper, we discuss a fibre optic sensor design with three tightly encapsulated fibres for multipurpose and multivalent sensing. It has the potential to integrate more detection and measurement techniques into a small space, and this, in turn, largely contributes to installation and cost optimizations and directly impacts investment plans and industrial success. The developed cable is tested in a specially developed high pressure and high temperature chamber. Furthermore, it is demonstrated that the proposed sensor cable offers the possibility of detection and distributed measurement of temperature, pressure, bending and vibrations. ARTICLE HISTORY

Triggered-lightning experiments at Camp Blanding, Florida, with emphasis on the lightning interaction with power distribution systems, are reviewed. Both overhead lines and underground cables are considered. The principal results are discussed.

A solution method is presented for problem of elastic space membranes supported by elastic flexible cables. Both membrane and cable undergo large deflections. Starting from the minimal surface the membrane is prestressed by imposed boundary displacements under the self-weight. Then an iterative procedure is employed, which consists in solving the membrane and the cable large deflection problems separately in each iteration step and checking the continuity of displacements and forces between membrane and cable. The procedure is repeated until convergence is achieved. Both membrane and cable problems are solved using the Analog Equation Method (AEM). The displacements as well as the stress resultants are evaluated at any point of the membrane and the cable from the integral representations of the solution of the substitute problems. An example problem is presented which illustrates the method and demonstrate its efficiency and accuracy.

This paper studies the coupled motion of an aircraft towing a cable for applications such as precision deployment or retrieval of payloads, or close surveying of land/ocean environments. There is a complex interaction between the motion of the cable tow-point, aerodynamic drag, and tension forces on the motion of the cable tip. The path-planning algorithm involves determining the motion of the aircraft, as well as the cable deployment rate, to achieve precision "hits" of the cable tip with known ground targets in a three-dimensional space. By utilizing the motion of the towed-body as a differentially flat output, the aircraft controls and/or reel rate are computed via an inverse technique. The motion of the towed-body is approximated using Chebyshev polynomials so as to pass through the desired points while minimizing its overall acceleration. The technique is implemented in a nonlinear programming environment to constrain the aircraft dynamics to within acceptable limits.

Using a cryogenic electro-optic sampling technique, we have studied the transient propagation characteristics of superconducting and normal indium lines in the picosecond regime. Transient dispersion effects, including increa.'!ed rise time and increased pulse width, the introduction of ringing on the waveform, and a novel "pulse sharpening" were observed. A model that takes into consideration the effects of modal dispersion and superconducting complex conductivity was established, and an algorithm was developed that accurately describes ail of the experimental findings.

In this paper, a technique to generate the wrench-closure workspace for general case completely restrained cable driven parallel mechanisms is proposed. Existing methods can be classified as either numerically or analytically based approaches. Numerical techniques exhaustively sample the task space, which can be inaccurate due to discretisation and is computationally expensive. In comparison, analytical formulations have higher accuracy, but often provides only qualitative workspace information. The proposed hybrid approach combines the high accuracy of the analytical approach and the algorithmic versatility of the numerical approach. Additionally, this is achieved with significantly lower computational costs compared to numerical methods. It is shown that the wrench-closure workspace can be reduced to a set of univariate polynomial inequalities with respect to a single variable of the end-effector motion. In this form, the workspace can then be efficiently determined and quantitati...

This paper proposes a new technique in power line protection, the adaptive noncommunication protection. In this technique, protection relays make operate or restraint decisions, adapting to system and fault conditions, without the need for communication links. Operation without communication links to signal the remote end relay is achieved by the detection and identification of the operation of the circuit breaker at the remote end of the protected line section. An algorithm based on the symmetric components is proposed to detect and identify the balance condition of the system during the fault. The paper is focused on one of the three protection schemes based on the new technique, the delayed operation scheme. Simulation studies carried out for various systems and fault conditions have demonstrated the feasibility of the scheme.

Radiation and temperature induced voltages and associated currents (generally termed RIEMF and TIEMF, respectively) have been found to occur in both MI coaxial cables and ceramic coated single cables. This is an important issue because TIEMF will make extremely difficult, if not impossible, to separate the radiation and temperature effects from the required signal for the ITER magnetic diagnostic coils. For operation in ITER, the problem is expected to be worse, the varying neutron energy spectrum and dose over the whole cable path, will give rise to a non-uniform transmutation and could induce TIEMF effects, even in initially perfect cables. It has been previously reported that TIEMF are generated in well localized regions of the central conductor (inhomogeneities). This paper present a model that explains observed TIEMF features and also some predictions concerning the EMF induced at the integrators input. Of particular importance is that some geometric configurations expected to be problematic, result in almost zero TIEMF despite the above mentioned effects, providing a more optimistic view of this problem. Some solutions are provided to mitigate cabling issues.

The development of cost-effective management strategies, including mapping of the submerged cultural heritage-potentially extensive even at quite great depths-is becoming ever more important, given increasing commercial activity in marine areas which may cause damage or prevent further investigation of the sea floor. This commercial activity can take the form of aggregate extraction, fishing, installation of facilities such as windmills, cables or pipelines and the construction of bridges, harbours etc. Non-invasive acoustic survey methods play a significant role in the mapping of the submerged cultural heritage. Elements such as archaeological wreck sites exposed on the sea floor are mapped using side-scan and multi-beam techniques. These can also provide information on bathymetric patterns representing potential Stone Age settlements, whereas the detection of such archaeological sites and wrecks partially or wholly embedded in the sea-floor sediments demands the application of highresolution sub-bottom profilers. This paper presents a strategy for the cost-effective large-scale mapping of unknown sedimentembedded sites such as submerged Stone Age settlements or wrecks, based on sub-bottom profiling with chirp systems. The mapping strategy described includes: a) definition of line spacing depending on the target; b) interactive sailing, i.e. when potential archaeological anomalies are located, their character is immediately investigated in more detail by a denser pattern of sub-bottom survey lines; c) on-site interpretation while acquiring data; d) recognition of anomalies not due to geology. Consequently, this strategy differs from those employed in detailed studies of known wreck sites (eg. Plets et al. 2009) and from the way in which geologists map the sea floor and the geological column beneath it. The strategy has been developed on the basis of extensive practical experience gained from the use of an off-the-shelf 2D chirp system and, given the present state of the technology, appears well-suited to large-scale maritime archaeological mapping.

Power cables that have sheaths, usually lead, and are manufactured with bitumen impregnated hessian which degrades over time, act as long grounding electrodes or inject fault current directly into the surrounding soil. As a consequence of this, the MV lines made of this type of cable spontaneously form a very large and complex grounding system around the high-voltage/medium-voltage (HV/MV) distribution substations. The area encompassed by this type of grounding system is much larger than the area occupied by the HV/MV substation itself. Due to this, the grounding system exhibits excellent performance, including a very low value of impedance to ground. The problem with this type of grounding system appears only at the design stage of the HV/MV substation, when safety conditions inside and in the vicinity of this substation should be confirmed by calculation. This paper provides improvements in accuracy to the only existing practical method developed for the analysis of this type of grounding system. The proposed improvement enables a more accurate estimation of active cable line length, grounding impedance of the cable line, the urban area covered by this type of grounding system, as well as grounding impedance of the entire grounding system.

In this paper, a novel evolutionary algorithm-based approach to optimal design of multimachine power system stabilizers (PSSs) is proposed. The proposed approach employs the particle swarm optimization (PSO) technique to search for optimal settings of PSS parameters. Two elgenvalue-based objective functions to enhance system damping of electromechanical modes are considered. The robustness of the proposed approach to the initial guess is demonstrated. The performance of the proposed PSO-based PSS (PSOPSS) under different disturbances, loading conditions, and system configurations is tested and examined for different multimachine power systems. Eigenvalue analysis and nonlinear simulation results show the effectiveness of the proposed PSOPSSs to damp out the local as well as the interarea modes of oscillations and work effectively over a wide range of loading conditions and system configurations. In addition, the potential and superiority of the proposed approach over the conventional approaches are demonstrated.

The physical environment in which transmission and distribution networks operate can have a significant impact on the resulting reliability of the power system. Extreme weather conditions can create an excessive physical stress on overhead lines resulting in sharp increases in the failure rate. This significantly increases the chance of overlapping failures during this period. This paper briefly illustrates the conventional two weather state model used to incorporate the effect of fluctuating weather in reliability assessment. The failures that can occur in extreme adverse weather are incorporated by utilizing a three weather state model. A multi-state weather modeling concept is introduced to reflect the effect of continuously varying stress created by the weather. A series of weather models are developed and used to assess the reliability indices associated with a two line parallel redundant circuit. This paper clearly shows that assessments without recognizing the weather can be ...

Residual impedance correction in impedance analyzers when using an asymmetrical test fixture needs three reference measurements, usually open circuit, short circuit, and load (meaning an impedance close to the impedance under test). This paper provides an error estimate for impedance measurements that apply a simple open/short correction in spite of using an asymmetrical test fixture. Experimental results show that the minimal error is obtained for impedance values close to the geometric mean of the short-circuit and open-circuit impedances, and that the theoretical prediction is indeed an upper limit for the actual error.

A new generation of PVC compounds for cables with very low values of smoke acidity have been developed, with the aim to reduce the emission of hydrochloric acid due to the combustion of cables in a fire. The use of several acid scavengers, capable to react quickly with HCl, trapping it in the ashes, and blocking the release of HCl in gas phase, have been evaluated. Two technical standards have been performed for making the measurements of the smoke acidity: EN 60754/1 and EN 60754/2.The results obtained with the above-mentioned standards have been compared, in order to understand if the presence of a temperature regime or a different setting of temperature can affect the measurements.

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Time domain reflectometry ͑TDR͒ technology has become a valuable tool for detecting displacements and locating shear planes in rock or soil slopes. It is based on transmitting an electromagnetic pulse into a coaxial cable grouted in rock or soil mass and watching for reflections of this transmission due to cable deformity induced by the ground deformation. Early detection of localized shear deformation in soft soils and quantifying the shear displacement using TDR remains a challenging work. The TDR response due to localized shear deformation is affected by cable resistance, soil-grout-cable interaction, and shear bandwidth. A comprehensive TDR wave propagation model considering cable resistance is introduced to model TDR response to cable deformity. Effects of the influencing factors on the relationship between the reflection spike and the shear displacement are investigated through laboratory tests and numerical simulations. The implications to enhancing TDR response and quantifying shear displacement are stressed. Practical suggestions are made, including procedure for correcting resistance effect, selection of cable and grout, and how to quantify shear displacement using TDR.

This paper presents the design and preliminary evaluation of an elastic lower-body exoskeleton. Human legs behave in a spring-like fashion while running. We selected a design that relied solely on material elasticity to store and release energy during the stance phase of running. The exoskeleton included a novel knee joint with a cam and a Bowden cable transferring energy to and from a waist-mounted extension spring. We used a friction-lock clutch controlled by hip angle via a pneumatic cylinder to release the cable during swing phase for free movement of the leg. The design also incorporated a composite leaf spring to store and release energy in the distal portion of the exoskeleton about the foot and ankle. Preliminary test data for our target subject showed that his typical leg deflection was 0.11 m with leg stiffness of 16 kN/m while running at 3.0 m/s. We used these values to set the desired stiffness (60%±15% of the normal leg stiffness, or 9.6±2.4 kN/m) and deflection (0.11 m) of the exoskeleton. We created simplified multi-body and full finite element quasi-static models to achieve the desired system stiffness and validate our results, respectively. The final design model had an overall stiffness of 7.3 kN/m, which was within the desired range. We fabricated a single-leg prototype of the exoskeleton that weighed 7.1 kg. We tested the exoskeleton stiffness quasi-statically and found a stiffness of 3.6 kN/m. While running, the exoskeleton provided ∼30% of the total leg stiffness for two subjects. Although the stiffness was lower than desired, the fabricated prototype demonstrated the ability of a quasi-passive exoskeleton to provide a significant portion of an individual's leg stiffness while running. Copyright c 2009 by ASME ability. In this sense the elastic exoskeleton could take on the role of a body-weight support system that does not need to be used in a laboratory environment. Typical body-weight support systems are large, bulky and not suitable for daily use. Development of a lightweight low-profile wearable exoskeleton that supports a significant portion of body weight could be used for locomotion rehabilitation in the wearer's home and natural surroundings.

The last decades the concern of the public, regarding the possible affects from the exposure to magnetic and electric fields, has grown considerably. This is because the generation, transmission and distribution of electric power are accompanied with the presence of the above mentioned fields. This paper attempts to illustrate the values of the resultant magnetic field in the low frequency

Bluetooth is a low-cost, low-power technology initially intended as a replacement of cables between electronic devices. Bluetooth devices can form small network of upto 8 devices called piconets. The specification also defines networks of piconets called scatternets. Scatternets can have various uses such as for "monitoring" purposes in factories and warehouses or for ad hoc meetings. Scatternets require the use of a routing scheme to find paths in a dynamic network. Though considerable research has been done in the area of routing in ad hoc networks, the direct application of this may be inefficient to Bluetooth scatternets. Some previous work has also presented routing schemes for scatternets, but this does not present any results showing the performance of the routing scheme. In this paper, we present a routing scheme for Bluetooth scatternets which is based on the Zone Routing Protocol. We motivate the design of the routing scheme keeping in mind the specifics of the Bluetooth technology. We present simulation results for the scheme which show that the scheme gives very low overhead while keeping the route acquisition latencies low. The routing information at a node does not require a large amount of storage. In fact, a parameter in the scheme can be varied to trade-off storage information and routing overhead versus route acquisition latency.

In cables, near resonance time-varying loading causes large amplitude oscillations mainly involving the resonant mode. A relevant contribution of higher modes may arise as a result of nonlinear coupling phenomena. In this work, analytical and finite element models are used to study the modal interactions in both planar and spatial responses to harmonic in-plane and out-of-plane loads. The aim of the investigation is to compare the two approaches by examining the effectiveness of the analytical model in describing the response with few degrees of freedom and the ability of the nonlinear finite element procedure adopted to capture the complex features of cable dynamics, albeit limited to stable oscillation branches. The analyses first explore a moderately taut cable and are then extended to the behavior of a slacker cable, in order to validate the simplifying kinematic assumptions introduced in the analytical models by comparing the obtained results with those furnished by the richer finite element models.

\Vorsak Kanok-Nukulchai, born in 1948, received his B. Eng. and M. Eng., respectively, from Chulalongkorn University and the Asian Institute of Technology, and his Ph. D. from University of California at Berkeley. He has been an active researcher in the field of computa-tional ...

Large technical systems serving the everyday needs of people, such as water supply systems, power grids or communication networks, are rich in accumulated metals. Over time, parts of these systems have been taken out of use without the system infrastructure being removed from its original location. Such metal stocks in hibernation thus constitute potential resource reservoirs accessible for recovery. In this paper, obsolete stocks of copper situated in the local power grids of two Swedish cities are quantified. Emphasis is also on economic conditions for extracting such -hibernating‖ cables. The results show that on a per customer basis, the two power grids contain similar amounts of copper, i.e. 0.04-0.05 tonnes per subscriber. However, the share of the copper stock that is in hibernation differs between the grids. In the larger grid of Gothenburg, almost 20% of the copper accumulated in the grid is no longer in use, while the obsolete share does not exceed 5% in the city of Linköping. For managers of local power grids, recovery of hibernating cables could be beneficial if integrated with other maintenance work on the grid. At the present price of copper, however, separate recovery of obsolete cables is not economically justified.

The Cornell 10-GeV Electron Synchrotron, built in 1968 for fixed-target physics, has served since 1979 as injector to the storage ring CESR. In this mode, which calls for a sparse fill pattern (45 bunches at most), the original beam position monitors are ineffective. An improved system, now under construction, is described.

The flexibility and low damping of the long-span suspended cables in the suspension bridges make them prone to vibrations due to wind and moving loads, which affect the dynamic response of the suspended cables and the bridge deck. This paper shows the design of two control schemes to control the nonlinear vibrations in the suspended cable and the bridge deck due to a vertical load moving on the bridge deck with a constant speed. The first control scheme is an optimal state feedback controller. The second control scheme is a robust state feedback controller, whose design is based on the design of optimal controllers. The proposed controllers, whose design is based on Lyapunov theory, guarantee the asymptotic stability of the system. A vertical cable between the bridge deck and the suspended cable is used to install a hydraulic actuator able to generate the active control force on the bridge deck. The MATLAB software is used to simulate the performance of the system with the designed controllers. The simulation results indicate that the proposed controllers are capable of significantly reducing the nonlinear oscillations of the system. In addition, the performance of the system with the proposed controllers is compared to the performance of the system controlled with a velocity feedback controller. It is found that the system with the proposed controllers can provide better performance than the system with the velocity feedback controller.

This paper presents an instrument for real-time emulation of digital subscriber loop binders. The instrument is based on the accurate description of the transmission channels characteristics and the binder's crosstalk envi- ronment. A key feature of the presented instrument is its ability to support single and multiple lines. In the multiple lines configuration, the pair-to-pair crosstalk injection is based on the actual data transmitted over the disturber lines and is achieved using analytical emulation of the pair-to-pair crosstalk coupling effects.

Magnetic field spot measurements were done at four distribution substations, three of them were of exactly the same design and capacity, while the fourth has similar design and half the capacity. The data collected were compared with one another. Taking into account loading of the substation during measurement period, it was found that magnetic field distributions were similar, with high