By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor?

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

A. hysteresis loss
B. field copper loss
C. armature copper loss
D. eddy current loss

Which of the following motors one will choose to drive the rotary compressor ?

A. D.C. shunt motor
B. D.C. series motor
C. Universal motor
D. Synchronous motor

Which one of the following is not the function of pole shoes in a D.C. machine ?

A. To reduce eddy current loss
B. To support the field coils
C. To spread out flux for better uniformity
D. To reduce the reluctance of the magnetic path

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

In a differentially compounded D.C. motor, if shunt field suddenly opens____________?

A. the motor will first stop and then run in opposite direction as series motor
B. the motor will work as series motor and run at slow speed in the same direction
C. the motor will work as series motor and run at high speed in the same direction
D. the motor will not work and come to stop

The plugging gives the____________?

A. zero torque braking
B. smallest torque braking
C. highest torque braking
D. none of the above