DC Motors In variable speed motor A weaker commutating field is needed at low speed than at high speed Same commutating field is needed at low speed than at high speed None of these A stronger commutating field is needed at low speed than at high speed A weaker commutating field is needed at low speed than at high speed Same commutating field is needed at low speed than at high speed None of these A stronger commutating field is needed at low speed than at high speed ANSWER DOWNLOAD EXAMIANS APP
DC Motors In D.C. machines the residual magnetism is of the order of 10 to 15 percent 2 to 3 percent 20 to 25 percent 50 to 75 percent 10 to 15 percent 2 to 3 percent 20 to 25 percent 50 to 75 percent ANSWER DOWNLOAD EXAMIANS APP
DC Motors If the speed of a dc shunt motor is increased the back emf of the motor will Remains same Decrease Increase Become zero Remains same Decrease Increase Become zero ANSWER DOWNLOAD EXAMIANS APP
DC Motors The running speed of a dc series motor is basically determined by Load Field excitation Armature reaction None of the listed here Load Field excitation Armature reaction None of the listed here 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
DC Motors If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens Nothing will happen to motor This will make armature to take heavy current, possibly burning it Motor will come to stop This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses Nothing will happen to motor This will make armature to take heavy current, possibly burning it Motor will come to stop This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses ANSWER DOWNLOAD EXAMIANS APP
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