DC Motors MCQs

Question 1

Which motor should be used for centrifugal pumps?

Accepted Answer

Shunt motor

Answer

Series motor

Answer

Either of the above

Answer

None of the above

Question 2

Which of the following methods is most effective in finding out the no load losses in a large D.C. shunt motor?

Accepted Answer

Swinburne's test

Answer

Field's test

Answer

Ward-Leonard test

Answer

Block rotor test

Question 3

A D.C. motor can be easily identified bY

Accepted Answer

commutator

Answer

winding

Answer

size of conductor

Answer

yoke

Question 4

The function of a field regulator for compound motors is to

Accepted Answer

control the flux

Answer

limit the armature current

Answer

demagnetise the field partially

Answer

none of the above

Question 5

The main disadvantage of Hopkinson's test for finding efficiency of the shunt D.C. motors is that it

Accepted Answer

requires two identical shunt machines

Answer

needs one motor and one generator

Answer

requires full-load power

Answer

ignores any change in iron loss

Question 6

Ward-Leonard system of speed control is not recommended for

Accepted Answer

constant speed operation

Answer

very low speeds

Answer

frequent motor reversals

Answer

wide speed range

Question 7

Which of the following tests can be used to determine no-load losses in a D.C. shunt motor?

Accepted Answer

Swinburne's test

Answer

Running down test

Answer

Field test

Answer

Brake test

Question 8

In regenerative braking

Accepted Answer

motor is made to run as a generator

Answer

motor energy is dissipated as heat

Answer

motor energy is dissipated in armature heatig

Answer

motor energy is dissipated in winding losses

Question 9

Regenerative braking on shunt motors is used when

Accepted Answer

the load acts as a braking force

Answer

the load is variable

Answer

the load is constantly decreasing

Answer

the load has overhauling characteristics.