The back e.m.f. of a synchronous motor depends on______________?
The back e.m.f. of a synchronous motor depends on______________?
A. speed
B. load
C. load angle
D. all of the above
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The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as___________?
The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as___________?A. pull-up torque
B. pull-in torque
C. pull-out torque
D. none of the aboveSlip rings are usually made of__________?
Slip rings are usually made of__________?A. carbon or graphite
B. brass or steel
C. silver or gold
D. copper or aluminiumThe maximum torque which a synchronous motor will develop at rest for any angular position of the rotor, at rated stator supply voltage and frequency, is known as__________?
The maximum torque which a synchronous motor will develop at rest for any angular position of the rotor, at rated stator supply voltage and frequency, is known as__________?A. locked-rotor torque
B. synchronous torque
C. pull up torque
D. reluctance torqueIn a synchronous motor, the armature current has large values for____________?
In a synchronous motor, the armature current has large values for____________?A. high excitation only
B. low excitation only
C. both high and low excitation
D. none of the aboveIn a 3-phase, 4-pole, 50 Hz synchronous motor, the frequency, pole number and load torque all are halved. The motor speed will be____________?
In a 3-phase, 4-pole, 50 Hz synchronous motor, the frequency, pole number and load torque all are halved. The motor speed will be____________?A. 3000 r.p.m.
B. 1500 r.p.m.
C. 750 r.p.m.
D. none of the aboveHunting in a synchronous motor cannot be due to___________?
Hunting in a synchronous motor cannot be due to___________?A. windage friction
B. variable load
C. variable frequency
D. variable supply voltage