A dc shunt generator, when driven without any excitation, showed an open circuit voltage of 12 V. When the field winding was excited, the voltage dropped to zero. It happened because

Electrical Machines
A dc shunt generator, when driven without any excitation, showed an open circuit voltage of 12 V. When the field winding was excited, the voltage dropped to zero. It happened because

there was a break in the armature circuit

field winding was wrongly connected

field resistance was higher than critical resistance

there was no residual magnetism in the field circuit

there was a break in the armature circuit

field winding was wrongly connected

field resistance was higher than critical resistance

there was no residual magnetism in the field circuit

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Electrical Machines
In a synchronous generator, if mechanical input is increased with constant excitation, the load angle will

either increase or decrease

increase

decrease

None of these

either increase or decrease

increase

decrease

None of these

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Electrical Machines
Compensating windings are used in DC generators

mainly to reduce the eddy currents by providing local short circuit.

None of these

to provide path for the circulation of cooling air.

to neutralize the cross magnetizing effect of the armature reaction.

mainly to reduce the eddy currents by providing local short circuit.

None of these

to provide path for the circulation of cooling air.

to neutralize the cross magnetizing effect of the armature reaction.

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Electrical Machines
A part an alternator winding consist of eight coils in series, each having an emf of 20 V rms induced in it. Coils are placed in successive slots and between each slot and the next, there is an electrical phase displacement of 30°. Find the emf of eight coils in series

76.91 V.

56.91 V.

66.91 V.

86.91 V.

76.91 V.

56.91 V.

66.91 V.

86.91 V.

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Electrical Machines
Poles of DC machine are often laminated to

reduce pulsation loss.

reduce iron weight.

dissipate more heat.

reduce armature reaction.

reduce pulsation loss.

reduce iron weight.

dissipate more heat.

reduce armature reaction.

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Electrical Machines
The direction of rotation of a 3 - ÃŽÂ¦ induction motor can be reversed by

transposing all the three leads from the supply.

disconnecting any one phase.

transposing any two leads from slip rings.

transposing any two leads from supply.

transposing all the three leads from the supply.

disconnecting any one phase.

transposing any two leads from slip rings.

transposing any two leads from supply.

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Electrical Machines

Electrical Machines A dc shunt generator, when driven without any excitation, showed an open circuit voltage of 12 V. When the field winding was excited, the voltage dropped to zero. It happened because

Electrical Machines In a synchronous generator, if mechanical input is increased with constant excitation, the load angle will

Electrical Machines Compensating windings are used in DC generators

Electrical Machines A part an alternator winding consist of eight coils in series, each having an emf of 20 V rms induced in it. Coils are placed in successive slots and between each slot and the next, there is an electrical phase displacement of 30°. Find the emf of eight coils in series

Electrical Machines Poles of DC machine are often laminated to

Electrical Machines The direction of rotation of a 3 - ÃŽÂ¦ induction motor can be reversed by

Electrical Machines
A dc shunt generator, when driven without any excitation, showed an open circuit voltage of 12 V. When the field winding was excited, the voltage dropped to zero. It happened because

Electrical Machines
In a synchronous generator, if mechanical input is increased with constant excitation, the load angle will

Electrical Machines
Compensating windings are used in DC generators

Electrical Machines
A part an alternator winding consist of eight coils in series, each having an emf of 20 V rms induced in it. Coils are placed in successive slots and between each slot and the next, there is an electrical phase displacement of 30°. Find the emf of eight coils in series

Electrical Machines
Poles of DC machine are often laminated to

Electrical Machines
The direction of rotation of a 3 - ÃŽÂ¦ induction motor can be reversed by