DC motors are stopped by opening line switches and not by forcing the handle of the motor starter back to OFF position. This is due to occurance of

Electrical Machines
DC motors are stopped by opening line switches and not by forcing the handle of the motor starter back to OFF position. This is due to occurance of

Both of above.

Heavy sparking at brushes.

None of these.

Heavy sparking at the first stud of starting resistance steps.

Both of above.

Heavy sparking at brushes.

None of these.

Heavy sparking at the first stud of starting resistance steps.

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Electrical Machines
If the load current and flux of a DC motor are held constant and voltage applied across it armature is increased by 5%, the speed of the motor will

Depends on other factor.

Reduce by 5%.

Remain unchanged.

Increase by 5%.

Depends on other factor.

Reduce by 5%.

Remain unchanged.

Increase by 5%.

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Electrical Machines
The armature of DC motor is laminated

to reduce the eddy current loss.

to reduce the inductor.

to reduce the mass.

to reduce the hysteresis loss.

to reduce the eddy current loss.

to reduce the inductor.

to reduce the mass.

to reduce the hysteresis loss.

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Electrical Machines
Which of the following will vary the maximum torque?

None of these

rotor resistance R

rotor reactance X

both 1 and 2

None of these

rotor resistance R

rotor reactance X

both 1 and 2

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Electrical Machines
In a 3-phase induction motor, if the supply voltage and frequency are reduced by the same ratio, then slip at which maximum torque occurs is

more and maximum torque decreases

less and maximum torque increases

less and maximum torque decreases

more and maximum torque remains constant

more and maximum torque decreases

less and maximum torque increases

less and maximum torque decreases

more and maximum torque remains constant

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Electrical Machines
A DC shunt generator builds up to a voltage of 220 V at no load while running at its rated speed. If the speed of the generator is raised by 25% kepping the circuit conditions unaltered, then the Voltage to which the machine would build up will

not change and remain at 220 V

increase to value lying between 220 V and 1.25 times 220 V

increase to 1.25 times 220 V

increase to a value greater than 1.25 times 220 V

not change and remain at 220 V

increase to value lying between 220 V and 1.25 times 220 V

increase to 1.25 times 220 V

increase to a value greater than 1.25 times 220 V

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Electrical Machines

Electrical Machines DC motors are stopped by opening line switches and not by forcing the handle of the motor starter back to OFF position. This is due to occurance of

Electrical Machines If the load current and flux of a DC motor are held constant and voltage applied across it armature is increased by 5%, the speed of the motor will

Electrical Machines The armature of DC motor is laminated

Electrical Machines Which of the following will vary the maximum torque?

Electrical Machines In a 3-phase induction motor, if the supply voltage and frequency are reduced by the same ratio, then slip at which maximum torque occurs is

Electrical Machines A DC shunt generator builds up to a voltage of 220 V at no load while running at its rated speed. If the speed of the generator is raised by 25% kepping the circuit conditions unaltered, then the Voltage to which the machine would build up will

Electrical Machines
DC motors are stopped by opening line switches and not by forcing the handle of the motor starter back to OFF position. This is due to occurance of

Electrical Machines
If the load current and flux of a DC motor are held constant and voltage applied across it armature is increased by 5%, the speed of the motor will

Electrical Machines
The armature of DC motor is laminated

Electrical Machines
Which of the following will vary the maximum torque?

Electrical Machines
In a 3-phase induction motor, if the supply voltage and frequency are reduced by the same ratio, then slip at which maximum torque occurs is

Electrical Machines
A DC shunt generator builds up to a voltage of 220 V at no load while running at its rated speed. If the speed of the generator is raised by 25% kepping the circuit conditions unaltered, then the Voltage to which the machine would build up will