In D.C. machines the residual magnetism is of the order of_________________?
In D.C. machines the residual magnetism is of the order of_________________?
A. 2 to 3 per cent
B. 10 to 15 per cent
C. 20 to 25 per cent
D. 50 to 75 per cent
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Differentially compound D.C. motors can find applications requiring___________?
Differentially compound D.C. motors can find applications requiring___________?
A. high starting torque
B. low starting torque
C. variable speed
D. frequent on-off cyclesWhich of the following test can be performed on DC series motor?
Which of the following test can be performed on DC series motor?
A. Swinburne test
B. Hopkinson test
C. Brake test
D. Field testThese days D.C. motors are widely used in____________?
These days D.C. motors are widely used in____________?
A. pumg sets
B. air compressors
C. electric traction
D. machine shopsIn Ward-Leonard control the lower limit of speed is imposed by________?
In Ward-Leonard control the lower limit of speed is imposed by________?
A. residual magnetism of the generator
B. core losses of motor
C. mechanical losses of motor and generator together
D. all of the aboveWhat will happen if the back e.m.f. of a D.C. motor vanishes suddenly?
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 noisyIf I2 be the armature current, then speed of a D.C. shunt motor is_______________?
If I2 be the armature current, then speed of a D.C. shunt motor is_______________?
A. independent of Ia
B. proportional to la
C. varies as (Ia)
D. varies as la