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

Heavy sparking at brushes.

Both of above.

Heavy sparking at the first stud of starting resistance steps.

None of these.

Heavy sparking at brushes.

Both of above.

Heavy sparking at the first stud of starting resistance steps.

None of these.

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Electrical Machines
If the excitation is critical, the power factor of the alternator is

leading power factor.

lagging power factor.

None of these

unity power factor.

leading power factor.

lagging power factor.

None of these

unity power factor.

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Electrical Machines
A 4 pole DC generator runs at 750 rpm and generate an emf of 240 V. The armature is wave wound and has 792 conductors. If the total flux from each pole is 0.0145 Wb. What is the leakage co-efficient?

1.2.

1.4.

1.8.

1.5.

1.2.

1.4.

1.8.

1.5.

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Electrical Machines
Which of the following machine is invariably provided with forced ventilation?

50 MW generator in a power plant.

Hermetically sealed motor of refrigerator.

Fractional horse power slow speed motor.

Fractional horse power high speed motor.

50 MW generator in a power plant.

Hermetically sealed motor of refrigerator.

Fractional horse power slow speed motor.

Fractional horse power high speed motor.

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Electrical Machines
In a DC machine the armature mmf is

stationary with respect to armature.

stationary with respect to field poles.

rotating with respect to field poles.

rotating with respect to field poles as well as armature.

stationary with respect to armature.

stationary with respect to field poles.

rotating with respect to field poles.

rotating with respect to field poles as well as armature.

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Electrical Machines
In a loaded DC motor, if the brushes are given a shift from the interpolar axis in the direction of rotation, then the commutation will

improve and the speed rises.

deteriorate and the speed rises.

deteriorate and the speed falls.

improve and the speed falls.

improve and the speed rises.

deteriorate and the speed rises.

deteriorate and the speed falls.

improve and the speed falls.

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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 excitation is critical, the power factor of the alternator is

Electrical Machines A 4 pole DC generator runs at 750 rpm and generate an emf of 240 V. The armature is wave wound and has 792 conductors. If the total flux from each pole is 0.0145 Wb. What is the leakage co-efficient?

Electrical Machines Which of the following machine is invariably provided with forced ventilation?

Electrical Machines In a DC machine the armature mmf is

Electrical Machines In a loaded DC motor, if the brushes are given a shift from the interpolar axis in the direction of rotation, then the commutation 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 excitation is critical, the power factor of the alternator is

Electrical Machines
A 4 pole DC generator runs at 750 rpm and generate an emf of 240 V. The armature is wave wound and has 792 conductors. If the total flux from each pole is 0.0145 Wb. What is the leakage co-efficient?

Electrical Machines
Which of the following machine is invariably provided with forced ventilation?

Electrical Machines
In a DC machine the armature mmf is

Electrical Machines
In a loaded DC motor, if the brushes are given a shift from the interpolar axis in the direction of rotation, then the commutation will