DGVCL Exam Paper (11-12-2011)
The efficiency of a transformer at full load, 0.8 p.f. lag is 90%. Its efficiency at full load, 0.8 p.f. lead will be

80 %
More than 90%
90 %
Less than 90%

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DGVCL Exam Paper (11-12-2011)
DC series motors are best suited for traction work because

Torque and speed are inversely proportional to the square of the armature current
Its torque is proportional to the square of the armature current and speed is inversely proportional to torque
Torque and speed are proportional to the square of the armature current
Its torque is proportional to the square of the armature current and speed is directional proporational to torque

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DGVCL Exam Paper (11-12-2011)
The purpose of skewing of rotor slots in an induction motor is

To increase the distributuion factor
To reduce the locking tendency of the rotor
To increase the breadth factor
To reduce the magnetic hum of the motor

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DGVCL Exam Paper (11-12-2011)
The corona effect can be minimized by increasing

Spacing between the conductors
Both spacing between the conductors and diameter of the conductor
Diameter of the conductor
The length of the conductor

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