Related Questions

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
If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens
A Nothing will happen to the motor
B This will make armature to take heavy current, possibly burning it
C This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses
D Motor will run at very slow speed
In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be
A Almost negligible
B Rated full-load current
C Less than full-load current
D More than full-load current
The current drawn by the armature of D.C. motor is directly proportional to
A The torque required
B The speed of the motor
C The voltage across the terminals
D None of the above
If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will
A Increase
B Decrease
C Remain same
D Become zero
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 run at constant speed
The ratio of starting torque to running torque in a synchronous motor is
A zero
B one
C two
D infinity
As the load is applied to a synchronous motor, the motor takes more armature current because
A The increased load has to take more current
B The rotor by shifting its phase backward causes motor to take more current
C The back e.m.f. decreases causing an increase in motor current
D The rotor strengthens the rotating field causing more motor current
In case the back e.m.f. and the speed of a D.C. motor are doubled, the torque developed by the motor will
A Remain unchanged
B Reduce to one-fourth value
C Increase four folds
D Be doubled
While starting a salient pole synchronous motor by induction motor action and connecting field discharge resistance across field, starting and accelerting torque is produced by
A induction motor torque in field winding
B induction motor torque in damper winding
C eddy current and hysteresis torque in pole faces
D reHetance motor torque due to saliency of the rotor
E all of the above methods

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