DC Motors Excessive sparking at brushes may be caused due to Dirt on the commutator Misaligment of machine Worn bearings Loose coupling Dirt on the commutator Misaligment of machine Worn bearings Loose coupling ANSWER DOWNLOAD EXAMIANS APP
DC Motors In a dc machines the residual magnetism is of the order of 10 to 15 percent 20 to 25 percent 50 to 75 percent 2 to 3 percent 10 to 15 percent 20 to 25 percent 50 to 75 percent 2 to 3 percent ANSWER DOWNLOAD EXAMIANS APP
DC Motors In a D.C. generator, the iron losses mainly take place in Commutator Yoke Armature rotor Armature conductors Commutator Yoke Armature rotor Armature conductors ANSWER DOWNLOAD EXAMIANS APP
DC Motors Excessive motor vibration is caused by Open armature coil Too much brush tension Worn bearings Bent shaft Open armature coil Too much brush tension Worn bearings Bent shaft ANSWER DOWNLOAD EXAMIANS APP
DC Motors As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit A resistance is connected in series with armature A resistance is connected parallel to the armature A high value resistor is connected across the field winding Armature is temporarily open circuited A resistance is connected in series with armature A resistance is connected parallel to the armature A high value resistor is connected across the field winding Armature is temporarily open circuited ANSWER DOWNLOAD EXAMIANS APP
DC Motors In case the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be Around 90% Anywhere between 75% and 90% 1 Less than 50% Around 90% Anywhere between 75% and 90% 1 Less than 50% ANSWER DOWNLOAD EXAMIANS APP
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