Electrical Machines In a synchronous machine, if the field flux axis is ahead of the armature field axis in the direction of rotation, the machine operating is asynchronous motor. synchronous motor. asynchronous generator. synchronous generator. asynchronous motor. synchronous motor. asynchronous generator. synchronous generator. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines To achieve spark less commutation brushes of DC generator are rocked ahead so as to bring them just ahead of magnetic neutral axis. in magnetic neutral axis. None of these just behind the magnetic neutral axis. just ahead of magnetic neutral axis. in magnetic neutral axis. None of these just behind the magnetic neutral axis. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Resistance commutation is used generally in case of None of these fractional kW DC machines. DC machines above 10 kW. DC machines bellow 5 kW. None of these fractional kW DC machines. DC machines above 10 kW. DC machines bellow 5 kW. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to 0.5 p.u 0.25 p.u 0.125 p.u 0.75 p.u 0.5 p.u 0.25 p.u 0.125 p.u 0.75 p.u ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The rotor speed of an induction motor is given by Ns = 120f / p × ( 1 - s ). Ns = 120f /p × ( 1 - r). Nr = 120f / p × (1-s). None of these Ns = 120f / p × ( 1 - s ). Ns = 120f /p × ( 1 - r). Nr = 120f / p × (1-s). None of these ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In induction motor the 7th harmonic torque may make the motor rotate at (1 / 7)th synchronous speed. This is called crawling. harmonics. resonance. cogging. crawling. harmonics. resonance. cogging. ANSWER DOWNLOAD EXAMIANS APP
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