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

None of these.

Both of above.

Heavy sparking at the first stud of starting resistance steps.

Heavy sparking at brushes.

None of these.

Both of above.

Heavy sparking at the first stud of starting resistance steps.

Heavy sparking at brushes.

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Electrical Machines
A 500 V, 120 KW, 50 Hz, star connected synchronous motor operating at 0.8 power factor leading has full load efficiency of 91%. The armature resistance is equal to 0.08Ω. The magnitude of armature current is nearly equal to

173 A.

240 A.

127 A.

190 A.

173 A.

240 A.

127 A.

190 A.

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Electrical Machines
In case of DC shunt motor if load is reduced

The speed will increase abruptly.

DC Shunt Motor

The speed will increase in proportion to reduction in load.

The speed will remains almost constant.

The speed will increase abruptly.

DC Shunt Motor

The speed will increase in proportion to reduction in load.

The speed will remains almost constant.

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Electrical Machines
A 230 V, 50 Hz, 4 pole single phase induction motor is rotating in the clockwise ( forward ) direction at a speed of 1425 rpm. If the rotor resistance at standstill is 7.8 ÃŽÂ©. Then the effective rotor resistance in the backward branch of the equivalent circuit will be

8 ÃŽÂ©.

2 ÃŽÂ©.

4 ÃŽÂ©.

10 ÃŽÂ©.

8 ÃŽÂ©.

2 ÃŽÂ©.

4 ÃŽÂ©.

10 ÃŽÂ©.

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Electrical Machines
Flashing the field of DC generator means

making the magnetic losses forces parallel.

increasing flux density by adding extra turns of winding.

neutralising residual magnetism.

creating residual magnetism by a DC source.

making the magnetic losses forces parallel.

increasing flux density by adding extra turns of winding.

neutralising residual magnetism.

creating residual magnetism by a DC source.

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Electrical Machines
The crawling in the induction motor is caused by

harmonics developed in the motor

high loads

low voltage supply

improper design of stator laminations

harmonics developed in the motor

high loads

low voltage supply

improper design of stator laminations

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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 A 500 V, 120 KW, 50 Hz, star connected synchronous motor operating at 0.8 power factor leading has full load efficiency of 91%. The armature resistance is equal to 0.08Ω. The magnitude of armature current is nearly equal to

Electrical Machines In case of DC shunt motor if load is reduced

Electrical Machines A 230 V, 50 Hz, 4 pole single phase induction motor is rotating in the clockwise ( forward ) direction at a speed of 1425 rpm. If the rotor resistance at standstill is 7.8 ÃŽÂ©. Then the effective rotor resistance in the backward branch of the equivalent circuit will be

Electrical Machines Flashing the field of DC generator means

Electrical Machines The crawling in the induction motor is caused by

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
A 500 V, 120 KW, 50 Hz, star connected synchronous motor operating at 0.8 power factor leading has full load efficiency of 91%. The armature resistance is equal to 0.08Ω. The magnitude of armature current is nearly equal to

Electrical Machines
In case of DC shunt motor if load is reduced

Electrical Machines
A 230 V, 50 Hz, 4 pole single phase induction motor is rotating in the clockwise ( forward ) direction at a speed of 1425 rpm. If the rotor resistance at standstill is 7.8 ÃŽÂ©. Then the effective rotor resistance in the backward branch of the equivalent circuit will be

Electrical Machines
Flashing the field of DC generator means

Electrical Machines
The crawling in the induction motor is caused by