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- Question
Polyphase generators produce simultaneous multiple sinusoidal voltages that are separated by
Options- A. certain constant phase angles
- B. certain constant frequencies
- C. certain constant voltages
- D. certain constant currents
- Correct Answer
- certain constant phase angles
- 1. In a Y-connected circuit, the magnitude of each line current is
Options- A. one-third the phase current
- B. three times the corresponding phase current
- C. equal to the corresponding phase current
- D. zero Discuss
- 2. In a balanced three-phase load, each phase has
Options- A. an equal amount of power
- B. one-third of total power
- C. two-thirds of total power
- D. a power consumption equal to
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Discuss
- 3. In a △-connected source feeding a Y-connected load,
Options- 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 Discuss
- 4. In a three-phase system, when the loads are perfectly balanced, the neutral current is
Options- A. zero
- B. one-third of maximum
- C. two-thirds of maximum
- D. at maximum Discuss
- 5. The most common type of ac motor is the
Options- A. single-phase induction motor
- B. two-phase induction motor
- C. three-phase induction motor
- D. two-phase squirrel-cage motor Discuss
- 6. In a △-connected source driving a △-connected load, the
Options- 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 Discuss
- 7. A constant load power means a uniform conversion of
Options- A. mechanical to electrical energy
- B. electrical to mechanical energy
- C. current to voltage
- D. voltage to current Discuss
- 8. A single-phase sinusoidal voltage of 120 V is connected to a 90 Ω load. Current in the circuit is
Options- A. 13.3 mA
- B. 133 mA
- C. 1.33 A
- D. 6.2 A Discuss
- 9. 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 Ω.
Options- 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 Discuss
- 10. In a Y-Y source/load configuration, the
Options- 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 Discuss
Three-Phase Systems in Power Applications problems
Search Results
Correct Answer: equal to the corresponding phase current
Correct Answer: an equal amount of power
Correct Answer: each phase voltage equals the difference of the corresponding load voltages
Correct Answer: zero
Correct Answer: three-phase induction motor
Correct Answer: load voltage, line voltage, and source phase voltage are all equal for a given phase
Correct Answer: electrical to mechanical energy
Correct Answer: 1.33 A
Correct Answer: single-phase 16 A; three-phase 8 A
Correct Answer: phase current, the line current, and the load current are all equal in each phase
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