A 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 efficiency when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

Electrical Machines
A 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 efficiency when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

82.5%

67.5%

72.5%

78.5%

82.5%

67.5%

72.5%

78.5%

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Electrical Machines
No load saturation characteristics are plotted between

short circuit current and armature current

no load voltage and armature current

short circuit current and field current

no load voltage and field current

short circuit current and armature current

no load voltage and armature current

short circuit current and field current

no load voltage and field current

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Electrical Machines
The damper windings also called the squirrel cage windings or damper grids

are provided on the stator for improving power factor.

both (A) and (B).

consists of short-circuited copper bars embedded in the field pole faces.

are provided in a synchronous motor to make it self starting.

are provided on the stator for improving power factor.

both (A) and (B).

consists of short-circuited copper bars embedded in the field pole faces.

are provided in a synchronous motor to make it self starting.

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Electrical Machines
In DC machines shape of net flux density is?

sine wave

peaky in nature

flat tapped or trapezoidal

saddle shape

sine wave

peaky in nature

flat tapped or trapezoidal

saddle shape

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Electrical Machines
A flat compound generator is obtained from compound generator by connecting a variable resistor

in series with the shunt field

in parallel with the shunt field

in parallel with the series field

in series with the series field

in series with the shunt field

in parallel with the shunt field

in parallel with the series field

in series with the series field

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Electrical Machines
In a resistance split phase motor, what is the range of torque angle?

0°

25° to 30°

90°

70° to 85°

0°

25° to 30°

90°

70° to 85°

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Electrical Machines

Electrical Machines A 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 efficiency when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

Electrical Machines No load saturation characteristics are plotted between

Electrical Machines The damper windings also called the squirrel cage windings or damper grids

Electrical Machines In DC machines shape of net flux density is?

Electrical Machines A flat compound generator is obtained from compound generator by connecting a variable resistor

Electrical Machines In a resistance split phase motor, what is the range of torque angle?

Electrical Machines
A 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 efficiency when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

Electrical Machines
No load saturation characteristics are plotted between

Electrical Machines
The damper windings also called the squirrel cage windings or damper grids

Electrical Machines
In DC machines shape of net flux density is?

Electrical Machines
A flat compound generator is obtained from compound generator by connecting a variable resistor

Electrical Machines
In a resistance split phase motor, what is the range of torque angle?