Three Phase AC circuits

Calculate the line voltage and Line current in this balanced Y-Y system:

• Eline = 1.38 KV

  Iline = 0.5312

• Eline = 13.8 KV

  Iline = 5.312 A

• Eline = 7.967 KV

  Iline = 5.312 A

• Eline = 7.967 KV

  Iline = 0.5312

Calculate phase voltage and phase current in this balanced Y-Y system:

• Ephase(source) = 7.967 kV

  Iphase(source) = 5.312 KA

• Ephase(source) = 7.967 V

  Iphase(source) = 5.312 A

• Ephase(source) = 7.967 kV

  Iphase(source) = 5.312 A

• Ephase(source) = 7.967 V

  Iphase(source) = 5.312 A

Calculate the total power consumed in this balanced Y-Y system:

• 1.2696 kW

• 126.96 W

• 12.696 kW

• 126.96 kW

In a three-phase system, the voltages are separated by

• 45⁰

• 90⁰

• 120⁰

• 180⁰

In a three-phase system, when the loads are perfectly balanced, the neutral current is

• zero

• one-third of maximum

• two-thirds of maximum

• at maximum

In a -connected source driving a -connected load, the

• load voltage and line voltage are one-third the source voltage for a given phase

• load voltage and line voltage are two-thirds the source voltage for a given phase

• load voltage and line voltage cancel for a given phase

• load voltage, line voltage, and source phase voltage are all equal for a given phase

Three ideal inductors are connected in star. The combination is supplied from a balanced three phase ac supply. The power consumed by the circuit will be

• infinite

• $\sqrt{3}\times VL\times IL\times\cos\theta$

• zero

• $3\times Vph\times Iph\times\cos\theta$

Three ideal inductors are connected in star. The combination is supplied from a balanced three phase ac supply. The power factor of the circuit will be...

• 1

• 0.5

• 0.866

• 0

Three practical inductors are connected in delta. The combination is supplied from a balanced three phase ac supply. The power factor of the circuit will be...

• 1

• 0

•  $\infty>pf>0$  

•  $0<pf<1$  

Three pure resisrors are connected in delta. The combination is supplied from a balanced three phase ac supply. The power factor of the circuit will be...

• 1

• 0

•  $\infty>pf>0$  

•  $0<pf<1$