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L27 3 ph-ac

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S
Satyakam

This document discusses delta connected systems with balanced loads. It contains information about line and phase voltages and currents in delta connected systems. It also contains the phasor diagram for a delta connected system with balanced loads and the relationship between line and phase currents. It provides an example problem calculating resistance, inductance, active power and reactive power for a delta connected system with three coils taking a line current of 5A at 0.8 power factor lagging.

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ELE101/102 Dept of E&E,MIT Manipal 1 The line emfs are: 240EE 120EE 0EE O BR O YB o RY −∠= −∠= ∠= In a delta connected system the line and phase emfs are the same R Y B Y  B  R  RYE ∧ YBE ∧ BRE ∧ ' ' ' phBBLBR phYYLYB phRRLRY EEEE EEEE EEEE === === === Delta Connected System
ELE101/102 Dept of E&E,MIT Manipal 2 Delta Connected System - Balanced Load R Y B Z Z Z YI ∧ BI ∧ RYV ∧ YBV ∧ BRV ∧ RYI ∧ YBI ∧ RI ∧ BRI ∧ )IIII( 0III III III III LBYR BYR YBBRB RYYBY BRRYR === =++ −= −= −= The line currents are
ELE101/102 Dept of E&E,MIT Manipal 3 B I ∧ RI ∧ YI ∧ BR I ∧ YB I ∧ − YB I ∧ RY I ∧ BR I ∧ − RY I ∧ − 1 2 0 ° 3 0 ° φ RYV ∧ YBV ∧ BRV ∧ Delta Connected – Balanced Load Complete phasor diagram:
ELE101/102 Dept of E&E,MIT Manipal 4 BI ∧ RI ∧ YI ∧ BRI ∧ YBI ∧ − YBI ∧ RYI ∧ BRI ∧ − RYI ∧ − 1 2 0 ° 3 0 ° Relation between The line & phase currents Delta Connected – Balanced Load phL phL o ph o ph o BR o RYR BRRYR I3I )(30cosI2I cos30Icos30I cos30Icos30I|I| III = °= −= −= −=
ELE101/102 Dept of E&E,MIT Manipal 5 )(sinIV3powerReactive )(cosIV3 )(cos 3 I V3 )(cosIVpowerActive LL LL L L phph φ= φ= φ= φ=3 Note: Φ is the phase angle between phase voltage and phase current Delta Connected – Balanced Load
ELE101/102 Dept of E&E,MIT Manipal 6 Three coils are connected in delta to a 3 Φ, 3 wire, 415 V, 50 Hz supply and take a line current of 5 A, 0.8 p.f lagging. a) Calculate the resistance and inductance of the coils. b) Draw the phasor diagram c) Find the active and reactive power Illustration VAR Ra Ans ph 2156Q2875W;P(c) H0.274L115;)( : TT == ==
ELE101/102 Dept of E&E,MIT Manipal 6 Three coils are connected in delta to a 3 Φ, 3 wire, 415 V, 50 Hz supply and take a line current of 5 A, 0.8 p.f lagging. a) Calculate the resistance and inductance of the coils. b) Draw the phasor diagram c) Find the active and reactive power Illustration VAR Ra Ans ph 2156Q2875W;P(c) H0.274L115;)( : TT == ==

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L27 3 ph-ac

  • 1. ELE101/102 Dept of E&E,MIT Manipal 1 The line emfs are: 240EE 120EE 0EE O BR O YB o RY −∠= −∠= ∠= In a delta connected system the line and phase emfs are the same R Y B Y  B  R  RYE ∧ YBE ∧ BRE ∧ ' ' ' phBBLBR phYYLYB phRRLRY EEEE EEEE EEEE === === === Delta Connected System
  • 2. ELE101/102 Dept of E&E,MIT Manipal 2 Delta Connected System - Balanced Load R Y B Z Z Z YI ∧ BI ∧ RYV ∧ YBV ∧ BRV ∧ RYI ∧ YBI ∧ RI ∧ BRI ∧ )IIII( 0III III III III LBYR BYR YBBRB RYYBY BRRYR === =++ −= −= −= The line currents are
  • 3. ELE101/102 Dept of E&E,MIT Manipal 3 B I ∧ RI ∧ YI ∧ BR I ∧ YB I ∧ − YB I ∧ RY I ∧ BR I ∧ − RY I ∧ − 1 2 0 ° 3 0 ° φ RYV ∧ YBV ∧ BRV ∧ Delta Connected – Balanced Load Complete phasor diagram:
  • 4. ELE101/102 Dept of E&E,MIT Manipal 4 BI ∧ RI ∧ YI ∧ BRI ∧ YBI ∧ − YBI ∧ RYI ∧ BRI ∧ − RYI ∧ − 1 2 0 ° 3 0 ° Relation between The line & phase currents Delta Connected – Balanced Load phL phL o ph o ph o BR o RYR BRRYR I3I )(30cosI2I cos30Icos30I cos30Icos30I|I| III = °= −= −= −=
  • 5. ELE101/102 Dept of E&E,MIT Manipal 5 )(sinIV3powerReactive )(cosIV3 )(cos 3 I V3 )(cosIVpowerActive LL LL L L phph φ= φ= φ= φ=3 Note: Φ is the phase angle between phase voltage and phase current Delta Connected – Balanced Load
  • 6. ELE101/102 Dept of E&E,MIT Manipal 6 Three coils are connected in delta to a 3 Φ, 3 wire, 415 V, 50 Hz supply and take a line current of 5 A, 0.8 p.f lagging. a) Calculate the resistance and inductance of the coils. b) Draw the phasor diagram c) Find the active and reactive power Illustration VAR Ra Ans ph 2156Q2875W;P(c) H0.274L115;)( : TT == ==
  • 7. ELE101/102 Dept of E&E,MIT Manipal 6 Three coils are connected in delta to a 3 Φ, 3 wire, 415 V, 50 Hz supply and take a line current of 5 A, 0.8 p.f lagging. a) Calculate the resistance and inductance of the coils. b) Draw the phasor diagram c) Find the active and reactive power Illustration VAR Ra Ans ph 2156Q2875W;P(c) H0.274L115;)( : TT == ==