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

940 RPM

920 RPM

960 RPM

970 RPM

940 RPM

920 RPM

960 RPM

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Electrical Machines
For a given torque, reducing diverter resistance of a DC series motor causes

decrease in speed demanding less armature current.

increase in speed but armature currnet remains the same.

increase in speed demanding more armature current.

decrease in speed but armature current remains the same.

decrease in speed demanding less armature current.

increase in speed but armature currnet remains the same.

increase in speed demanding more armature current.

decrease in speed but armature current remains the same.

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Electrical Machines
Under operating conditions the rotor conductor should be _________________ in induction motor.

always closed.

semi closed or semi opened.

always opened.

none.

always closed.

semi closed or semi opened.

always opened.

none.

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Electrical Machines
Stray losses in transformer occurs in

transformer insulating oil.

winding conductors and steel structures of transformer.

paper insulation in transformers.

steel core.

transformer insulating oil.

winding conductors and steel structures of transformer.

paper insulation in transformers.

steel core.

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Electrical Machines
Saving of copper in auto transformer is increased as compared to two winding transformer, when transformation ratio K approaches to

two.

unity.

infinity.

zero.

two.

unity.

infinity.

zero.

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Electrical Machines
The no load and full load speed of DC motor are 1400 rpm and 1200 rpm respectively. What is the percentage speed regulation of the motor ?

14.28%.

15.30%.

18.25%.

16.67%.

14.28%.

15.30%.

18.25%.

16.67%.

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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 For a given torque, reducing diverter resistance of a DC series motor causes

Electrical Machines Under operating conditions the rotor conductor should be _________________ in induction motor.

Electrical Machines Stray losses in transformer occurs in

Electrical Machines Saving of copper in auto transformer is increased as compared to two winding transformer, when transformation ratio K approaches to

Electrical Machines The no load and full load speed of DC motor are 1400 rpm and 1200 rpm respectively. What is the percentage speed regulation of the motor ?

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
For a given torque, reducing diverter resistance of a DC series motor causes

Electrical Machines
Under operating conditions the rotor conductor should be _________________ in induction motor.

Electrical Machines
Stray losses in transformer occurs in

Electrical Machines
Saving of copper in auto transformer is increased as compared to two winding transformer, when transformation ratio K approaches to

Electrical Machines
The no load and full load speed of DC motor are 1400 rpm and 1200 rpm respectively. What is the percentage speed regulation of the motor ?