Electrical Interview Question

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

A. 45°
B. 90°
C. 120°
D. 180°

Answer: Option C


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

A. zero
B. one-third of maximum
C. two-thirds of maximum
D. at maximum

Answer: Option A

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

A. load voltage and line voltage are one-third the source voltage for a given phase
B. load voltage and line voltage are two-thirds the source voltage for a given phase
C. load voltage and line voltage cancel for a given phase
D. load voltage, line voltage, and source phase voltage are all equal for a given phase

Answer: Option D

4. In a certain three-wire Y-connected generator, the phase voltages are 2 kV. The magnitudes of the line voltages are

A. 2,000 V
B. 6,000 V
C. 666 V
D. 3,464 V

Answer: Option D


5. In a -connected source feeding a Y-connected load,

A. each phase voltage equals the difference of the corresponding load voltages
B. each phase voltage equals the corresponding load voltage
C. each phase voltage is one-third the corresponding load voltage
D. each phase voltage is 60° out of phase with the corresponding load voltage

 Answer: Option A


6. In a Y-Y source/load configuration, the

A. phase current, the line current, and the load current are all equal in each phase
B. phase current, the line current, and the load current are 120° out of phase
C. phase current and the line current are in phase, and both are 120° out of phase with the load current
D. line current and the load current are in phase, and both are out of phase with the phase current

Answer: Option A


7. In a Y-connected circuit, the magnitude of each line current is

A. one-third the phase current
B. three times the corresponding phase current
C. equal to the corresponding phase current
D. zero

Answer: Option C


8. A constant load power means a uniform conversion of

A. mechanical to electrical energy
B. electrical to mechanical energy
C. current to voltage
D. voltage to current

Answer: Option B


9. Referring to Problem 3, power consumption is

A. 16 W
B. 160 mW
C. 160 W
D. 3,459 W

Answer: Option C


10. A two-phase generator is connected to two 90 load resistors. Each coil generates 120 V ac. A common neutral line exists. How much current flows through the common neutral line?

A. 1.33 A
B. 1.88 A
C. 2.66 A
D. 1.77 A

Answer: Option D