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.Management Sciences
Category: D.C. Motors
One D.C. motor drives another D.C. motor. The second D.C. motor when excited and driven_______________?
A. runs as a generator
B. does not run as a generator
C. also runs as a motor comes to stop after sometime
The armature torque of the D.C. shunt motor is proportional to____________?
A. field flux only
B. armature current only
C. both A. and B.
D. none of the above
In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to
A. 100% of the previous value
B. 50% of the previous value
C. 25% of the previous value
D. 10% of the previous value
E. none of the above
The speed of a D.C. shunt motor can be increased by_______________?
A. increasing the resistance in armature circuit
B. increasing the resistance in field circuit
C. reducing the resistance in the field circuit
D. reducing the resistance in the armature circuit
In which of the following applications D.C. series motor is invariably tried?
A. Starter for a car
B. Drive for a water pump
C. Fan motor
D. Motor operation in A.C. or D.C
If the field winding resistance of a DC shunt motor is increases, its speed will____________?
If the field winding resistance of a DC shunt motor is increases, its speed will
A. decreases
B. increases
C. remains same
D. none of the above
Which of the following method of speed control of D.C. machine will offer minimum efficiency ?
A. Voltage control method
B. Field control method
C. Armature control method
D. All above methods
As -the load is increased the speed of D.C. shunt motor will____________?
A. reduce slightly
B. increase slightly
C. increase proportionately
D. remains unchanged
When two D.C. series motors are connected in parallel, the resultant speed is____________?
A. more than the normal speed
B. loss than the normal speed
C. normal speed
D. zero
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
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