DC Motors MCQs

Question 1

The eddy current losses vary as as Hysteresis loss in a de generator varies reversal where f is the frequency of magnetic flux

Accepted Answer

f

Answer

1/f

Answer

f2

Answer

1/j2

Question 2

A dc generator operates at constant speed, variable load, Which of the following losses is likely to be most significant?

Accepted Answer

copper loss

Answer

windage loss

Answer

eddy current loss

Answer

bearing friction loss

Question 3

A de simplex lap winding

Accepted Answer

has all the above features

Answer

is a completely closed winding

Answer

has a minimum number of brushes

Answer

has a number of parallel paths equal to the number of poles

Question 4

In a dc generator, windage loss is proportional to

Accepted Answer

square of armature speed

Answer

supply voltage

Answer

square of supply voltage

Answer

armature speed

Question 5

Iron losses in a dc machine take place in

Accepted Answer

armature rotor

Answer

yoke

Answer

commutator

Answer

armature conductors

Question 6

Hysteresis loss in dc machine is given by?1.6 is IV, where V is

Accepted Answer

volume of iron part

Answer

the voltage generated

Answer

peripheral velocity

Answer

volume of copper conductors

Question 7

Core losses in a dc machine occur in

Accepted Answer

both armature and pole faces

Answer

armature alone

Answer

pole faces alone

Answer

yoke alone

Question 8

A dc generator has commercial efficiency electrical efficiency tie and mechanical efficiency qm Then

Accepted Answer

Ile =

Answer

le = nc. Tim

Answer

#NAME?

Answer

lm=lc+Tle

Question 9

The open circuit voltage of a de compound generator is 200 V. At full load, the terminal voltage

Accepted Answer

will always be less than 200 V

Answer

will always be 200 V

Answer

will always be greater than 200 V

Answer

may be greater than or less than 200 V