Consider the following statements regarding dc machines : 1. possible resistance of shunt-field winding is 1 Ω 2. possible resistance of series-field winding is 1 Ω 3. electrographite brushes are used for 230 V, 10 A machines 4. Copper-graphite brushes are used for 230 V, 10 A machines 5. Possible armature-circuit resistance is 1 Ω From these, the correct statements are

Electrical Machines
Consider the following statements regarding dc machines : 1. possible resistance of shunt-field winding is 1 Ω 2. possible resistance of series-field winding is 1 Ω 3. electrographite brushes are used for 230 V, 10 A machines 4. Copper-graphite brushes are used for 230 V, 10 A machines 5. Possible armature-circuit resistance is 1 Ω From these, the correct statements are

2, 4 ,5

2, 3 , 5

1, 3, 5

1, 4

2, 4 ,5

2, 3 , 5

1, 3, 5

1, 4

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Electrical Machines
The rotor slots are slightly skewed in squirrel cage induction motor to

reduce the magnetic hum and locking tendency of rotor.

decrease the amount of copper to be used.

increase the strength of rotor bars.

provide ease of fabrication.

reduce the magnetic hum and locking tendency of rotor.

decrease the amount of copper to be used.

increase the strength of rotor bars.

provide ease of fabrication.

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Electrical Machines
To have sparkless commutation, the armature reaction effect in a DC machine is neutralized by

compensating winding and commutating poles.

increasing field excitation.

shifting the brush axis from GNA to MNA.

fixing the brush axis inline with the pole axis.

compensating winding and commutating poles.

increasing field excitation.

shifting the brush axis from GNA to MNA.

fixing the brush axis inline with the pole axis.

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Electrical Machines
The factors that are responsible for decrease in terminal voltage of a shunt generator are

reduction in field current, effect of armature reaction, armature.

armature resistance, inter poles, armature.

armature resistance, effect of armature reaction.

reduction in field current, effect of armature reaction, armature.

armature resistance, inter poles, armature.

armature resistance, effect of armature reaction.

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Electrical Machines
A 5 KVA transformer has a turns ratio of N1/N2 = 10. The impedance of primary winding is 3+j5 ohms while that of secondary winding is 0.5+j0.8 ohms. The impedance of transformer when referred to primary will be

53+j85 ohms

3.05+j5.08 ohms

8+j13 ohms

3.5+j5.8 ohms

53+j85 ohms

3.05+j5.08 ohms

8+j13 ohms

3.5+j5.8 ohms

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Electrical Machines
Which of the following machine will have maximum efficiency?

DC motor.

Electrical power transformer.

Induction motor.

Electrical power generator.

DC motor.

Electrical power transformer.

Induction motor.

Electrical power generator.

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Electrical Machines

Electrical Machines The rotor slots are slightly skewed in squirrel cage induction motor to

Electrical Machines To have sparkless commutation, the armature reaction effect in a DC machine is neutralized by

Electrical Machines The factors that are responsible for decrease in terminal voltage of a shunt generator are

Electrical Machines A 5 KVA transformer has a turns ratio of N1/N2 = 10. The impedance of primary winding is 3+j5 ohms while that of secondary winding is 0.5+j0.8 ohms. The impedance of transformer when referred to primary will be

Electrical Machines Which of the following machine will have maximum efficiency?

Electrical Machines
The rotor slots are slightly skewed in squirrel cage induction motor to

Electrical Machines
To have sparkless commutation, the armature reaction effect in a DC machine is neutralized by

Electrical Machines
The factors that are responsible for decrease in terminal voltage of a shunt generator are

Electrical Machines
A 5 KVA transformer has a turns ratio of N1/N2 = 10. The impedance of primary winding is 3+j5 ohms while that of secondary winding is 0.5+j0.8 ohms. The impedance of transformer when referred to primary will be

Electrical Machines
Which of the following machine will have maximum efficiency?