φA DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the speed when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

Electrical Machines
φA DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the speed when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

970 RPM

960 RPM

940 RPM

920 RPM

970 RPM

960 RPM

940 RPM

920 RPM

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Electrical Machines
Flux density under leading pole tips in case of generator will

None of these

decrease

increase

either increase or decrease

None of these

decrease

increase

either increase or decrease

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Electrical Machines
Which of the following is done in speed control of DC motor by field flux control?

Inserting resistance to armature circuit and field circuit.

Inserting an additional resistance in the field circuit.

Any of above.

Inserting an additional resistance in the armature circuit.

Inserting resistance to armature circuit and field circuit.

Inserting an additional resistance in the field circuit.

Any of above.

Inserting an additional resistance in the armature circuit.

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Electrical Machines
Larger values of air flux density is taken while designing IM for

larger output.

none.

larger bore diameter.

both.

larger output.

none.

larger bore diameter.

both.

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Electrical Machines
Two DC series motors are connected in series and are driving the same mechanical load. If the motors are now connected in parallel the speed will become

half.

4 times.

one fourth.

double.

half.

4 times.

one fourth.

double.

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Electrical Machines
A 4-pole DC generator runs at 1500 rpm. The frequency of current in the armature winding is:

Zero Hz.

100 Hz.

25 Hz.

50 Hz.

Zero Hz.

100 Hz.

25 Hz.

50 Hz.

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Electrical Machines

Electrical Machines φA DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the speed when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

Electrical Machines Flux density under leading pole tips in case of generator will

Electrical Machines Which of the following is done in speed control of DC motor by field flux control?

Electrical Machines Larger values of air flux density is taken while designing IM for

Electrical Machines Two DC series motors are connected in series and are driving the same mechanical load. If the motors are now connected in parallel the speed will become

Electrical Machines A 4-pole DC generator runs at 1500 rpm. The frequency of current in the armature winding is:

Electrical Machines
φA DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the speed when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

Electrical Machines
Flux density under leading pole tips in case of generator will

Electrical Machines
Which of the following is done in speed control of DC motor by field flux control?

Electrical Machines
Larger values of air flux density is taken while designing IM for

Electrical Machines
Two DC series motors are connected in series and are driving the same mechanical load. If the motors are now connected in parallel the speed will become

Electrical Machines
A 4-pole DC generator runs at 1500 rpm. The frequency of current in the armature winding is: