D.C. shunt motors are used for driving

If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens

A

This will make armature to take heavy current, possibly burning it

B

This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses

C

Nothing will happen to motor

D

Motor will come to stop

If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens

A

Nothing will happen to the motor

B

This will make armature to take heavy current, possibly burning it

C

This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses

D

Motor will run at very slow speed

In case of D.C. shunt motors the speed is dependent on back e.m.f. only because

A

Back e.m.f. is equal to armature drop

B

Armature drop is negligible

C

Flux is proportional to armature current

D

Flux is practically constant in D.C. shunt motors

In D.C. shunt motors as load is reduced

A

The speed will increase abruptly

B

The speed will increase in proportion to reduction in load

C

The speed will remain almost/constant

D

The speed will reduce

Which one of the following is not necessarily the advantage of D.C. motors over A.C. motors?

A

Low cost

B

Wide speed range

C

Stability

D

High starting torque

After driving for fifty kilo-meter, the driver suddenly realized that he has been driving in the wrong direction. Choose the wrong one following sentences.

A

After

B

realized

C

has been driving

D

in

After driving for twenty miles, he suddenly realized that he has benn driving in the wrong direction. Identify the word/phrase that must be changed in order for the sentences to be correct.

A

After driving

B

for

C

realized

D

has been driving

After driving (a) for twenty miles, he suddenly realized (b) that he has been driving (c) in (d) the wrong direction.

A

a

B

b

C

c

D

d

A moving-coil permanent-magnet instrument can be used as _____ by using a low resistance shunt.

A

ammeter

B

voltmeter

C

flux-meter

D

ballistic galvanometer

Starters are used with D.C. motors because

A

These motors have high starting torque

B

These motors are not self-starting

C

Back e.m.f. of these motors is zero initially

D

To restrict armature current as there is no back e.m.f. while starting

D.C. shunt motors are used for driving

Related Questions