1. The speed of a D.C. motor can be varied by varying ?

field current

applied voltage

resistance in series with armature

any of the above

Answer: any of the above

Explanation:


2. In a manual shunt motor starter ?

over load relay is connected in series and no volt relay in parallel with the load

over load relay is connected in parallel and no volt relay in series with the load

over load relay and no volt relay are both connected in series with the load

over load relay and no volt relay are both connected in parallel with the load

Answer: over load relay is connected in series and no volt relay in parallel with the load

Explanation:


3. One D.C. motor drives another D.C. motor. The second D.C. motor when excited and driven ?

runs as a generator

does not run as a generator

also runs as a motor

comes to stop after sometime

Answer: runs as a generator

Explanation:


4. A series motor is started without load. The effect is that ?

the back e.m.f. decreases

the torque increases rapidly

the speed increases rapidly

the current drawn increases rapidly

Answer: the speed increases rapidly

Explanation:


5. The variable resistor shunting the field of a D.C series motor is called a ?

armature divider

voltage regulator

field divertor

potential divider

Answer: field divertor

Explanation:


6. A D.C motor can be easily identified by ?

winding

commutator

size of conductor

yoke

Answer: commutator

Explanation:


7. In regenerative braking ?

motor energy is dissipated as heat

motor energy is dissipated in armature heating

motor energy is dissipated in windage losses

motor is made to run as a generator

Answer: motor is made to run as a generator

Explanation:


8. The losses occurring in a DC generator are given below, Which loss is likely to have highest proportion at rated load of the generator ?

hysteresis loss

field copper loss

armature copper loss

eddy current loss

Answer: armature copper loss

Explanation:


9. Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be ?

level compounded

under compounded

cumulatively compounded

differentially compounded

Answer: cumulatively compounded

Explanation:


10. Which of the following load normally, needs starting torque more than. The rated torque ?

Blowers

Conveyors

Air compressors

Centrifugal pumps

Answer: Conveyors

Explanation: