A 3-φ alternator has negligible stator resistance. A short circuit test is conducted on this alternator. At a particular speed, a field current of If1 is required to drive the rated armature current. If the speed of the alternator is reduced to half, the field current required to maintain rated armature current

Electrical Machines
A 3-φ alternator has negligible stator resistance. A short circuit test is conducted on this alternator. At a particular speed, a field current of If1 is required to drive the rated armature current. If the speed of the alternator is reduced to half, the field current required to maintain rated armature current

Cannot be predicted due to insufficient data.

Would be equal to If1/2.

Would be equal to If1.

Woud be equal to 2If1.

Cannot be predicted due to insufficient data.

Would be equal to If1/2.

Would be equal to If1.

Woud be equal to 2If1.

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Electrical Machines
The field system of an alternator is usually excited

3 - ÃŽÂ¦, 50 Hz and 400 V.

110 / 220 V AC.

250 / 250 V DC.

230 V AC.

3 - ÃŽÂ¦, 50 Hz and 400 V.

110 / 220 V AC.

250 / 250 V DC.

230 V AC.

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Electrical Machines
Which of the following DC Motor uses 4-point starter?

DC shunt motor with armature resistance.

DC compound motor.

DC series motor.

DC shunt motor with field weaking control.

DC shunt motor with armature resistance.

DC compound motor.

DC series motor.

DC shunt motor with field weaking control.

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Electrical Machines
In star-delta starting of squirrel cage induction motor compared to DOL starting the starting current and torque are

1/√3, 1/√3

1/3, 1/√3

1/√3, 1/3

1/3, 1/3

1/√3, 1/√3

1/3, 1/√3

1/√3, 1/3

1/3, 1/3

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Electrical Machines
For a DC machine having P no of pair of pole pairs, Z no of conductors having length L of resistivity ρ and cross section S are arranged. what is the armature resistance?

PZL/ 4Sa

PZL/4S

PZL/4Sp²

PZL/4Sa²

PZL/ 4Sa

PZL/4S

PZL/4Sp²

PZL/4Sa²

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Electrical Machines
The introduction of interpoles in between the main poles improves the performance of a dc machine, because

the inequality of air-gap flux on the top and bottom halves of the armature is removed

the flux waveform is improved with reduction in harmonics

the interpoles produce additional flux to augment the developed torque

a counter-emf is induced in the coil undergoing commutation

the inequality of air-gap flux on the top and bottom halves of the armature is removed

the flux waveform is improved with reduction in harmonics

the interpoles produce additional flux to augment the developed torque

a counter-emf is induced in the coil undergoing commutation

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Electrical Machines

Electrical Machines The field system of an alternator is usually excited

Electrical Machines Which of the following DC Motor uses 4-point starter?

Electrical Machines In star-delta starting of squirrel cage induction motor compared to DOL starting the starting current and torque are

Electrical Machines For a DC machine having P no of pair of pole pairs, Z no of conductors having length L of resistivity ρ and cross section S are arranged. what is the armature resistance?

Electrical Machines The introduction of interpoles in between the main poles improves the performance of a dc machine, because

Electrical Machines
The field system of an alternator is usually excited

Electrical Machines
Which of the following DC Motor uses 4-point starter?

Electrical Machines
In star-delta starting of squirrel cage induction motor compared to DOL starting the starting current and torque are

Electrical Machines
For a DC machine having P no of pair of pole pairs, Z no of conductors having length L of resistivity ρ and cross section S are arranged. what is the armature resistance?

Electrical Machines
The introduction of interpoles in between the main poles improves the performance of a dc machine, because