Alternators MCQs

Question 1

In a cylindrical rotor how much portion of the rotor is wound?

Accepted Answer

Two third

Answer

One third

Answer

Half

Answer

Full

Question 2

The speed of an alternator is changed from 3000 r.p.m. to 1500 r.p.m. The generated e.m.f./phase will become

Accepted Answer

half

Answer

one fourth

Answer

double

Answer

unchanged

Question 3

Zero power factor method for an alternator is generally used to determine

Accepted Answer

voltage regulation of the alternator

Answer

synchronous impedance of alternator

Answer

efficiency of alternator

Answer

none of the above

Question 4

In an alternator the armature reaction is mainly influenced by

Accepted Answer

the power factor of the load

Answer

short-circuit ratio

Answer

speed of the alternator

Answer

total current drawn

Question 5

Regulation of an alternator supplying resistive or inductive load is

Accepted Answer

always positive

Answer

always negative

Answer

either of the above

Answer

none of the above

Question 6

4 pole 1500 r.p.m. alternator will generate e.m.f. at

Accepted Answer

50 Hz

Answer

20 Hz

Answer

40 Hz

Answer

60 Hz

Question 7

To obtain sinusoidal flux distribution

Accepted Answer

chamfering of poles is done in salient pole alternators only

Answer

chamfering of poles is done in turboalternators only

Answer

either of the above

Answer

none of the above

Question 8

In air-crafts, alternators have operating frequency of

Accepted Answer

400 Hz

Answer

800 Hz

Answer

60 Hz

Answer

50 Hz

Question 9

Alternators, now a days, are designed to have poor regulation because

Accepted Answer

it limits the value of short circuit current

Answer

it reduces the construction cost

Answer

we employ automatic voltage regulators

Answer

none of the above