Synchronous Motors The back e.m.f. of a synchronous motor depends on All of these load angle speed load All of these load angle speed load ANSWER DOWNLOAD EXAMIANS APP
Synchronous Motors The pull out torque of a synchronous motor is generally ______ times its full-load torque. 6 to 9 1.25 to 3.5 0.5 5 to 10 6 to 9 1.25 to 3.5 0.5 5 to 10 ANSWER DOWNLOAD EXAMIANS APP
Synchronous Motors The duration of sudden short-circuit test on a synchronous motor is usually about one hour None of these one minute one second one hour None of these one minute one second ANSWER DOWNLOAD EXAMIANS APP
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 leading power factor with over-excitation no change of power factor leading power factor with under-excitation lagging power factor with over-excitation leading power factor with over-excitation no change of power factor leading power factor with under-excitation lagging power factor with over-excitation ANSWER DOWNLOAD EXAMIANS APP
Synchronous Motors Damper winding in a synchronous motor________ Serves to start the motor Improve pf of the motor Increases hunting of the motor Reduces windage losses Serves to start the motor Improve pf of the motor Increases hunting of the motor Reduces windage losses ANSWER DOWNLOAD EXAMIANS APP
Synchronous Motors A synchronous motor develop maximum power when load angle is 120° 90° 45° 60° 120° 90° 45° 60° ANSWER DOWNLOAD EXAMIANS APP
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