Electrical Machines Variation in speed by ward-Leonard control of DC motors occurs due to variation in Armature current. Armature voltage. Supply voltage. Field excitaion. Armature current. Armature voltage. Supply voltage. Field excitaion. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The armature mmf in a dc machine is 1. stationary with respect to field poles 2. stationary with respect to armature 3. rotating with respect to field poles 4. rotating with respect to armature From these, the correct answer is 2, 3 2, 4 1, 3 1, 4 2, 3 2, 4 1, 3 1, 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The power flow of a dc motor, with respect to a DC generator is reversed. none of these. modified. increased. reversed. none of these. modified. increased. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a loaded DC motor, if the brushes are given a shift from the interpolar axis in the direction of rotation, then the commutation will improve and the speed rises. deteriorate and the speed rises. deteriorate and the speed falls. improve and the speed falls. improve and the speed rises. deteriorate and the speed rises. deteriorate and the speed falls. improve and the speed falls. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In induction motor when the length of the air gap is increased, the magnetizing current of the motor increases while the short circuit current __________________. increased. kept constant to certain value. remains unchanged. decreased. increased. kept constant to certain value. remains unchanged. decreased. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following is/are the advantages of carbon brush over the copper brush? In case of any sparking they will be less damaged than copper brushes They are not hard as copper brush All of these They are self lubricating in nature In case of any sparking they will be less damaged than copper brushes They are not hard as copper brush All of these They are self lubricating in nature ANSWER DOWNLOAD EXAMIANS APP
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