Where D.C. motor of H.P. 12 or more requires frequent starting, stopg, reversing and speed control______________?
A. drum type controller is used
B. three point starter is used
C. four point starter is used
D. all above can be used
If the field of a D.C. shunt motor gets opened while motor is running______________?
A. the speed of motor will be reduced %
B. the armature current will reduce
C. the motor will attain dangerously high speed 1
D. the motor will continue to nuvat constant speed
Which of the following losses are significantly reduced by laminating the core of a D.C. generator ?
A. Hysteresis losses
B. Eddy current losses
C. Copper losses
D. Windage losses
Which of the following loss in a D.C. generator is dissipated in the form of heat?
A. Mechanical loss
B. Core loss
C. Copper loss
D. All of the above
What will happen if the back e.m.f. of a D.C. motor vanishes suddenly?
A. The motor will stop
B. The motor will continue to run
C. The armature may burn
D. The motor will run noisy
When the armature of a D.C. motor rotates, e.m.f. induced is___________?
A. self-induced e.m.f.
B. mutually induced e.m.f.
C. back e.m.f
D. none of the above
In a manual shunt motor starter?
A. over load relay is connected in series and no volt relay in parallel with the load
B. over load relay is connected in parallel and no volt relay in series with the load
C. over load relay and no volt relay are both connected in series with the load
D. over load relay and no volt relay are both connected in parallel with the load