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### EEE :: Three - Phase Systems in Power Applications

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

2.  A. 45° B. 90° C. 120° D. 180°

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

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

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

6.  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

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

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

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

10.  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

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

12.  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

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

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

15. A constant load power means a uniform conversion of

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

17. 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?

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

19. A single-phase sinusoidal voltage of 120 V is connected to a 90 load. Current in the circuit is

20.  A. 13.3 mA B. 133 mA C. 1.33 A D. 6.2 A