Electrical Engineering - Three-Phase Systems in Power Applications

Exercise :: Three-Phase Systems in Power Applications - General Questions

16. 

In a certain Y-Y system, the source phase currents each have a magnitude of 9 A. The magnitude of each load current for a balanced load condition is

A. 3 A
B. 6 A
C. 9 A
D. 27 A

Answer: Option C

Explanation:

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17. 

A three-phase -connected generator is driving a balanced load such that each phase current is 12 A in magnitude. When I θa = 12 30° A, what are the polar expressions for the other phase currents?

A. I θb = 12 150° A, I θc = 12–90° A
B. I θb = 12120° A, I θc = 1230° A
C. I θb = 1230° A, I θc = 12120° A
D. I θb = 1290° A, I θc = 1290° A

Answer: Option A

Explanation:

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18. 

In a Y-connected circuit, between each line voltage and the nearest phase voltage, there is a phase angle of

A.
B. 30°
C. 60°
D. 120°

Answer: Option B

Explanation:

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19. 

The most common type of ac motor is the

A. single-phase induction motor
B. two-phase induction motor
C. three-phase induction motor
D. two-phase squirrel-cage motor

Answer: Option C

Explanation:

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20. 

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

A. each phase of the load has one-third of the full line voltage across it
B. each phase of the load has two-thirds of the full line voltage across it
C. each phase of the load has the full line voltage across it
D. each phase of the load has a voltage across it equal to

Answer: Option C

Explanation:

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