Electrical Engineering - Three-Phase Systems in Power Applications

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

11. 

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

A. 0 A
B. 1.33 A
C. 3.99 A
D. 2.66 A

Answer: Option A

Explanation:

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12. 

Compare the total copper cross sections in terms of current-carrying capacity for a single-phase and a three-phase 120 V system with effective load resistance of 15 .

A. single-phase 32 A; three-phase 16 A
B. single-phase 16 A; three-phase 8 A
C. single-phase 8 A; three-phase 4 A
D. single-phase 16 A; three-phase 0 A

Answer: Option B

Explanation:

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13. 

If in a Y-connected ac generator, each phase voltage has a magnitude of 90 VRMS, what is the magnitude of each line voltage?

A. 0 V
B. 90 V
C. 156 V
D. 180 V

Answer: Option C

Explanation:

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14. 

Polyphase generators produce simultaneous multiple sinusoidal voltages that are separated by

A. certain constant phase angles
B. certain constant frequencies
C. certain constant voltages
D. certain constant currents

Answer: Option A

Explanation:

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15. 

In a balanced three-phase load, each phase has

A. an equal amount of power
B. one-third of total power
C. two-thirds of total power
D. a power consumption equal to IL

Answer: Option A

Explanation:

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