Electrical Machines Compensating windings are used in DC generators None of these to provide path for the circulation of cooling air. mainly to reduce the eddy currents by providing local short circuit. to neutralize the cross magnetizing effect of the armature reaction. None of these to provide path for the circulation of cooling air. mainly to reduce the eddy currents by providing local short circuit. to neutralize the cross magnetizing effect of the armature reaction. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a DC generator, if P be the number of poles and N be the rpm of the rotor, then frequency of magnetic reversals will be PN/120. PN/2. PN/60. PN/3000. PN/120. PN/2. PN/60. PN/3000. 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 1, 4 2, 3 2, 4 1, 3 1, 4 2, 3 2, 4 1, 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a 3 - Φ IM in order to eliminate cogging the number of stator slots must be either (B) or (C). equal to number of rotor slots. an integral multiple of number of rotor slots. unequal to number of rotor slots and skewed in shape. either (B) or (C). equal to number of rotor slots. an integral multiple of number of rotor slots. unequal to number of rotor slots and skewed in shape. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines DC motors are stopped by opening line switches and not by forcing the handle of the motor starter back to OFF position. This is due to occurance of Heavy sparking at brushes. None of these. Both of above. Heavy sparking at the first stud of starting resistance steps. Heavy sparking at brushes. None of these. Both of above. Heavy sparking at the first stud of starting resistance steps. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A transformer has resistance and reactance in per unit as 0.01 and 0.04 respectively. Its voltage regulation for 0.8 power factor lagging and leading will be 6% and -4% 3.2% and -1.6% 4.8% and -3.2% None of these 6% and -4% 3.2% and -1.6% 4.8% and -3.2% None of these ANSWER DOWNLOAD EXAMIANS APP
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