Alternators MCQs

Question 1

Voltage regulation of an alternator is usually

Accepted Answer

much higher than that of a power transformer

Answer

equal to that of power transformer

Answer

much lower than that of a power transformer

Answer

equal to that of induction motor

Question 2

In an alternator, the stator frame serves

Accepted Answer

as a return path for the flux

Answer

to verticate the armature

Answer

to hold the armature stampings

Answer

to protect the whole machine

Question 3

For a given output steam turbo-alternators are much smaller is size than water turbine-alternators because

Accepted Answer

steam turbo-alternators run at high speed

Answer

steam turbo-alternators are built with smaller capacities

Answer

steam turbo-alternators have long rotors

Answer

all of the above

Question 4

Alternator of a central power station will have

Accepted Answer

revolving field winding

Answer

revolving armature winding

Answer

either of the above

Answer

none of the above

Question 5

Non-salient pole type of rotor construction is usually provided in the alternators used in

Accepted Answer

thermal power stations

Answer

hydropower stations

Answer

either of the above

Answer

none of the above

Question 6

In an alternator terminal voltage rise will be more

Accepted Answer

when lagging load is thrown off

Answer

when leading load is thrown off

Answer

when unity power factor load is thrown off

Answer

none of the above

Question 7

Turbo-alternators usually have

Accepted Answer

2 poles

Answer

12 poles

Answer

8 poles

Answer

4 poles

Question 8

In an alternator short pitch coils are used

Accepted Answer

to reduce the harmonics in generated e.m.f.

Answer

to reduce the stray losses

Answer

to reduce the size of the machine

Answer

to provide accurate phase difference of 1200 between each phase

Question 9

If the input to the prime mover of an alternator is kept constant but the excitation is increased, then

Accepted Answer

kVA will be lagging

Answer

kVA with the leading

Answer

kW will be changed

Answer

the power factor of the load remains constant