Synchronous Generator MCQs Part 8

Synchronous Generator MCQs Part 8

Contents

The AC armature winding of an alternator operates at _____________ the field winding

The AC armature winding of an alternator operates at _____________ the field winding

1. Much lesser voltage than
2. Much higher voltage than
3. Same voltage as
4. None of the above

Correct answer: 2. Much higher voltage than

Turbo-alternators have rotors that have

Turbo-alternators have rotors that have:

1. Large diameter and small axial length
2. Small diameter and axial length
3. Small diameter and long axial length
4. Large diameter and long axial length

Correct answer: 3. Small diameter and long axial length

The effect of armature reaction in an alternator is minimum at power factor of

The effect of armature reaction in an alternator is minimum at power factor of

1. 0.866 lagging
3. Unity
4. 0.5 lagging

A 3-phase alternator has 3-slots per pole. The distribution factor of winding is

A 3-phase alternator has 3-slots per pole. The distribution factor of winding is:

1. 1
2. 0.25
3. 0.5
4. 0.866

Solution: Distribution factor Kd is

Kd = {sin (nβ/2}/{ n sin(β/2)}

Where in the above equation

n = slots per pole per phase

β = Angular displacement between slots = 180° per slots per pole

In the present case n = 3/3 = 1

β = 180°/3 = 60°

Kd = {sin (1*60°/2}/{ 1*sin(60°/2)} = 1

The rating of an alternator is expressed in

The rating of an alternator is expressed in:

1. HP
2. kW
3. kVA
4. kVAR