# Synchronous Generator MCQ Part 6

## Damper windings are employed in alternator to

Damper windings are employed in alternator to:

1. Reduce windage losses
2. Parallel multiple alternators
3. Prevent hunting
4. Achieve synchronism
5. 2 & 4

## When the alternator operates at a load power factor of unity, the effect of armature reaction is

When the alternator operates at a load power factor of unity, the effect of armature reaction is:

1. Partially distorting
2. Wholly distorting
3. Wholly magnetizing
4. Partially magnetizing

Explanation: When the alternator operates at a load power factor of unity, the effect of armature reaction is wholly distorting.

At unity power factor armature flux is in phase with induced EMF. For that instance the armature flux is in phase with induced EMF E. The field flux is in quadrature with E. As a result, the armature flux is in quadrature with main field field. Since the two fluxes are perpendicular to each other, at the unity power factor the armature reaction of alternators is wholly distorting.

## The voltage regulation of alternator depends on which factor

The voltage regulation of alternator depends on which factor:

2. Power factor
3. Both of these
4. None of these

Correct answer: 3. Both of these

## For which value of power factor the effect of armature reaction is minimum

For which value of power factor the effect of armature reaction is minimum:

1. 0.348
2. 0.5
3. 0.85
4. Unity