Alternators MCQs

Question 1

An alternator running in parallel with other alternators all having automatic voltage regulators is to be taken off the bus. The usual procedure before opening the switch is to

Accepted Answer

reduce the power fed to the primemover

Answer

reduce alternator excitation

Answer

increase alternator excitation

Answer

none of the above

Question 2

Due to which of the following reasons concentrated windings are not used in alternators?

Accepted Answer

Concentrated windings require deep slots for accommodation which leads to increased armature leakage and reactance

Answer

Concentrated windings increase voltage harmonics

Answer

Concen trated windings decrease induced e.m.f/phase

Answer

Concentrated windings increase copper-to-iron ratio thereby decreasing the capacity

Question 3

A stationary alternator should not be connected to a live bus-bar because it

Accepted Answer

will get short-circuited

Answer

will distrub generated e.m.fs. of other alternators connected in parallel

Answer

is likely to run as a synchronous motor

Answer

will decrease but-bar voltage though momentarily

Question 4

The power drawn by the prime-mover of an alternator, under no-load condition, goes to

Accepted Answer

meet no-load losses

Answer

meet copper losses both in armature and rotor windings

Answer

produce power in armature

Answer

produce e.m.f. in armature winding

Question 5

In a larger generator dampers

Accepted Answer

increase stability

Answer

reduce frequency fluctuations

Answer

reduce voltage fluctuations

Answer

none of the above

Question 6

The choice of field construction, in an alternator, is basically determined by

Accepted Answer

the kind of energy source available in the geographic location

Answer

generated voltage needed by the customers

Answer

comparative cost of the field systems

Answer

supply frequency required by the consumers

Question 7

The load between two steam-driven alternators operating in parallel may be adjusted by varying

Accepted Answer

steam supply to their prime movers

Answer

speed of the alternators

Answer

field strengths of the alternators

Answer

(b) power faciors of the alternators

Question 8

The overheating of generator winding result in

Accepted Answer

reduced life of the machine

Answer

does not have any significant effect

Answer

reduces generated voltage

Answer

reduces power factor

Question 9

The regulation of an alternator is likely to be negative in case of

Accepted Answer

leading power factor of the load

Answer

lagging power factor of the load

Answer

high speed alternators

Answer

low speed alternators