Alternators MCQs

Question 1

For the alternators operating in parallel, if the load shared by one of them is to be increased, its field excitation is

Accepted Answer

to be kept constant but input torque should be increased

Answer

to be weakened keeping input torque same

Answer

to be strengthened keeping input torque same

Answer

to be kept constant but input torque should be decreased

Question 2

Which of the following methods is best for finding the voltage regulation?

Accepted Answer

Potier triangle method

Answer

Synchronous impedance method

Answer

M.M.F. method

Answer

All are equally good

Question 3

For a 3-phase winding with 5 slots per pole per phase and with coil span of 12 slot pitch, the value of pitch factor is

Accepted Answer

0.951

Answer

0.851

Answer

0.98

Answer

1.05

Question 4

Salient pole rotors are used where

Accepted Answer

low and medium speed primemovers are available

Answer

high frequency current is required

Answer

floor space is available in plenty

Answer

high speed prime movers are available

Question 5

The power factor of an alternator is determined by its

Accepted Answer

load

Answer

primemover

Answer

excitation

Answer

speed

Question 6

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

Accepted Answer

the reactive component of the output is changed

Answer

the power factor of the load remains constant

Answer

the active component of the output is changed

Answer

none of the above

Question 7

For parallel operation, A.C. polyphase alternators must have the same

Accepted Answer

voltage rating

Answer

kVA rating

Answer

excitation

Answer

speed

Question 8

Unlike D.C. generator kW rating, alternators are rated in

Accepted Answer

kVA

Answer

MW

Answer

kVAR

Answer

kWh

Question 9

Dirt accumulation in generators can cause

Accepted Answer

none of the above

Answer

flashovers

Answer

overheating poor voltage regulation

Answer

(e) all of the above