Alternators MCQs

Question 1

The distribution factor, in alternators, is defined as the ratio of e.m.fs. of

Accepted Answer

distributed winding to concentrated winding

Answer

distributed winding to full pitch winding

Answer

concentrated winding to distributed winding

Answer

full pitch winding to distributed winding

Question 2

As load power factor of an alternator becomes more leading, the value of generated voltage required to give rated terminal voltage

Accepted Answer

decreases

Answer

increases

Answer

varies with rotor speed

Answer

remains unchanged

Question 3

In an alternator, the flux created by the armature m.m.f. subtracts directly from the main flux for the following conditions of the load

Accepted Answer

load power factor is zero lagging

Answer

load power factor is unity

Answer

load power factor is 0.6 lagging

Answer

load power factor is zero leading

Question 4

Synchronous impedance method of finding voltage regulation of an alternator is called pessimistic method because

Accepted Answer

it gives regulation value higher than is actually found by direct loading

Answer

it is simplest to perform and compute

Answer

armature reaction is wholly magnetizing

Answer

none of the above

Question 5

Two alternators are running in parallel. If the field of one of the alternators is adjusted it will

Accepted Answer

change its power factor

Answer

change its frequency

Answer

reduce its speed

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change its load

Question 6

In a synchronous machine, if the field flux axis is ahead of the armature field axis, in the direction of rotation, the machine is working as

Accepted Answer

synchronous generator

Answer

asynchronous generator

Answer

synchronous motor

Answer

asynchronous motor

Question 7

The advantage of salient poles in an alternator is

Accepted Answer

adaptability of low and medium speed operation

Answer

reduced winding loss

Answer

reduced bearing loads and noise

Answer

reduced noise

Question 8

For parallel operation of the two alternators, desirable feature is that both should have

Accepted Answer

less of resistance as compared to synchronous reactance

Answer

same reactance

Answer

same resistance

Answer

more of resitance as compared to synchronous reactance

Question 9

It two alternators are running in parallel and the excitation of one of the alternators is increased, then

Accepted Answer

wattless component will change

Answer

power output will decrease

Answer

machine with excess excitation will burn

Answer

both machies will start vibrating