Synchronous Generator MCQs Part 3

Synchronous Generator MCQs Part 3

High-speed alternators are driven using

High-speed alternators are driven using:

1. Steam engines
2. Steam turbines
3. Hydraulic turbines
4. None of these

Correct answer: 2. Steam turbines

If the excitation of an alternator operating in parallel with other alternators is decreased, then

If the excitation of an alternator operating in parallel with other alternators is decreased, then:

1. Its PF becomes more lagging
2. Its PF becomes more leading
3. Its output kW will change
4. None of the above

Correct answer: 2. Its PF becomes more leading

The power factor on which an alternator operates depends on

The power factor on which an alternator operates depends on:

1. Armature losses
2. Copper losses
3. Nature of load
4. Speed of prime mover

Correct answer: 3. Nature of load

In a synchronous generator, if Φ is the flux per pole and if f is the frequency of the EMF E induced, then which of following statement is correct

In a synchronous generator, if Φ is the flux per pole and if f is the frequency of the EMF E induced, then which of following statement is correct:

1. E ∝ Φf
2. E ∝ Φ/f
3. E ∝ 1/Φf
4. E ∝ 1/Φ

Correct answer: 1. E ∝ Φf

Explanation: RMS value of EMF is given mathematically by equation: E = 2.22 fΦZ, Therefore E ∝ Φf

Two alternators are operating in parallel, If the voltage of one of the two alternators suddenly falls, then which of following is correct

Two alternators are operating in parallel, If the voltage of one of the two alternators suddenly falls, then which of following is correct:

1. Both machines will stop
2. Alternator whose voltage suddenly decreases will stop
3. Both alternators will stop
4. Synchronous torque will come into operation to restore synchronism

Correct answer: 4. Synchronous torque will come into operation to restore synchronism