Synchronous Motors A synchronous motor connected to infinite bus-bars has at constant full load, 100% excitation and unity power factor. On changing the excitation only, the armature current will have lagging power factor with over-excitation leading power factor with under-excitation leading power factor with over-excitation no change of power factor lagging power factor with over-excitation leading power factor with under-excitation leading power factor with over-excitation no change of power factor ANSWER DOWNLOAD EXAMIANS APP
Synchronous Motors The direction of rotation of a synchronous motor can be reversed by reversing, Supply phase sequence Polarity of rotor poles Current to field winding None of the listed here Supply phase sequence Polarity of rotor poles Current to field winding None of the listed here ANSWER DOWNLOAD EXAMIANS APP
Synchronous Motors If the synchronous motor, properly synchronised to the supply is running on no load and is having negligible loss then the back e.m.f. will be more than the supply voltage the stator current will be very small the stator current will be zero the stator current will be very high the back e.m.f. will be more than the supply voltage the stator current will be very small the stator current will be zero the stator current will be very high ANSWER DOWNLOAD EXAMIANS APP
Synchronous Motors A synchronous motor runs at only one speed because it ______ Has no losses Is a doubly fed machine None of the listed here Has a damper winding Has no losses Is a doubly fed machine None of the listed here Has a damper winding ANSWER DOWNLOAD EXAMIANS APP
Synchronous Motors Dust and dirt accumulation on motor winding will result in Shorting of coils Increased core losses Eddy current flow Rise in winding temperature Shorting of coils Increased core losses Eddy current flow Rise in winding temperature ANSWER DOWNLOAD EXAMIANS APP
Synchronous Motors In case one phase of a three-phase synchronous motor is short-circuited the motor will not start take less than the rated load run at 2/3 of synchronous speed run with excessive vibrations not start take less than the rated load run at 2/3 of synchronous speed run with excessive vibrations ANSWER DOWNLOAD EXAMIANS APP
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