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%.

920 RPM

970 RPM

960 RPM

940 RPM

920 RPM

970 RPM

960 RPM

940 RPM

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Electrical Machines
The frame of an induction motor is made of

stainless steel.

closed grained cast iron.

silicon steel.

aluminium.

stainless steel.

closed grained cast iron.

silicon steel.

aluminium.

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Electrical Machines
The basic function of a transformer is to change

the frequency

the power factor

the power level

the level of the voltage

the frequency

the power factor

the power level

the level of the voltage

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Electrical Machines
In a DC machine

current and emf in armature are alternating.

emf in armature conductors and at the terminals is alternating.

current and emf in armature are unidirectional

current and emf at the terminals are alternating.

current and emf in armature are alternating.

emf in armature conductors and at the terminals is alternating.

current and emf in armature are unidirectional

current and emf at the terminals are alternating.

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Electrical Machines
A commutator with a diameter of 50 cm rotating at 1000 rpm. For a brush width of 1.5 cm, find the time of commutation in ms.

0.649.

0.573.

0.512.

0.443.

0.649.

0.573.

0.512.

0.443.

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Electrical Machines
Pole changing methods are suitable only for ___________ type induction motor.

wound.

cage.

linear.

none of these.

wound.

cage.

linear.

none of these.

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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 The frame of an induction motor is made of

Electrical Machines The basic function of a transformer is to change

Electrical Machines In a DC machine

Electrical Machines A commutator with a diameter of 50 cm rotating at 1000 rpm. For a brush width of 1.5 cm, find the time of commutation in ms.

Electrical Machines Pole changing methods are suitable only for ___________ type induction 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
The frame of an induction motor is made of

Electrical Machines
The basic function of a transformer is to change

Electrical Machines
In a DC machine

Electrical Machines
A commutator with a diameter of 50 cm rotating at 1000 rpm. For a brush width of 1.5 cm, find the time of commutation in ms.

Electrical Machines
Pole changing methods are suitable only for ___________ type induction motor.