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 no change of power factor leading power factor with under-excitation leading power factor with over-excitation lagging power factor with over-excitation no change of power factor leading power factor with under-excitation leading power factor with over-excitation ANSWER DOWNLOAD EXAMIANS APP
Synchronous Motors By which of the following methods the constant speed of a synchronous motor can be changed to new fixed value ? By changing the supply frequency By changing the applied voltage By interchanging any two phases By changing the load By changing the supply frequency By changing the applied voltage By interchanging any two phases By changing the load ANSWER DOWNLOAD EXAMIANS APP
Synchronous Motors The back e.m.f. of a synchronous motor depends on load angle All of these load speed load angle All of these load speed ANSWER DOWNLOAD EXAMIANS APP
Synchronous Motors In case one phase of a three-phase synchronous motor is short-circuited the motor will run with excessive vibrations not start run at 2/3 of synchronous speed take less than the rated load run with excessive vibrations not start run at 2/3 of synchronous speed take less than the rated load ANSWER DOWNLOAD EXAMIANS APP
Synchronous Motors A synchronous motor working at leading power factor can be used as Voltage booster Mechanical synchronizer Noise generator Phase advancer Voltage booster Mechanical synchronizer Noise generator Phase advancer ANSWER DOWNLOAD EXAMIANS APP
Synchronous Motors If one phase of a 3 phase synchronous motor is short circuited, motor Will fail to pull into step Will not come upto speed Will overheat in spots Will refused ro start Will fail to pull into step Will not come upto speed Will overheat in spots Will refused ro start ANSWER DOWNLOAD EXAMIANS APP
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