WorksheetsAC MOTORS
Total questions: 10
Worksheet time: 5mins
Synchronous motor can operate at
Lagging power factor only
Leading power factor only
Unity power factor only
Lagging, leading and unity power factor only.
An over excited synchronous motor draws current at
depends on the nature of load
unity power factor
leading power factor
lagging power factor.
With the increase in the excitation current of synchronous motor, the power factor of the motor will
decrease
remain constant
improve
depend on other factors.
In case the field of a synchronous motor is under excited, the power factor will be
lagging
leading
zero
unity.
Rotor winding of a synchronous motor is excited by
ac supply at 400 V
dc supply at 100 V - 250 V
Revolving field
Induction from stator currents.
When the excitation of an unloaded salient pole synchronous motor gets disconnected
the motor will stop
the motor will burn
the motor will run as a reluctance motor at the same speed
the motor will run as a reluctance motor at a lower speed.
Rotor winding of a synchronous motor is excited by
ac supply at 400 V
dc supply at 100 V - 250 V
Revolving field
Induction from stator currents.
The damping winding in a synchronous motor is generally used
to provide starting torque only
to reduce noise level
to reduce eddy currents
to prevent hunting and provide the starting torque.
The back emf set up in the stator of a synchronous motor will depend on
rotor excitation only
rotor speed only
rotor excitation and rotor speed
coupling angle, rotor speed and excitation.
Which of the following motors is non-self starting ?
synchronous motor
wound rotor induction motor
squirrel cage induction motor
dc series motor.
