Electrical Machines In a loaded DC generator, if the brushes are given a shift from the interpolar axis in the direction of rotation, then the commutation will deteriorate with fall of terminal voltage. improve with rise in terminal voltage. improve with fall of terminal voltage. deteriorate with rise in terminal voltage. deteriorate with fall of terminal voltage. improve with rise in terminal voltage. improve with fall of terminal voltage. deteriorate with rise in terminal voltage. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In dc machines, 1. reactance voltage is proportional to armature current 2.reactance voltage is proportional to core length 3.reactance voltage is due to self-flux of the coil undergoing commutation 4. armature-cross flux is neutralized by interpolar flux 5. interpolarmmf is more than armature mmf in the interpolar zone From these, the correct answer is 2, 3, 4 1, 2, 3, 4 1, 2, 5 1, 3, 5 2, 3, 4 1, 2, 3, 4 1, 2, 5 1, 3, 5 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Consider the following statements regarding dc machines : 1. possible resistance of shunt-field winding is 1 Ω 2. possible resistance of series-field winding is 1 Ω 3. electrographite brushes are used for 230 V, 10 A machines 4. Copper-graphite brushes are used for 230 V, 10 A machines 5. Possible armature-circuit resistance is 1 Ω From these, the correct statements are 2, 3 , 5 1, 3, 5 2, 4 ,5 1, 4 2, 3 , 5 1, 3, 5 2, 4 ,5 1, 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a 3-phase induction motor, if the supply voltage and frequency are reduced by the same ratio, then slip at which maximum torque occurs is more and maximum torque remains constant less and maximum torque increases more and maximum torque decreases less and maximum torque decreases more and maximum torque remains constant less and maximum torque increases more and maximum torque decreases less and maximum torque decreases ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If residual magnetism of a shunt generator is destroyed accidentally it may be restored by connecting its shunt field in reverse. to earth. to a DC source. to an AC source. in reverse. to earth. to a DC source. to an AC source. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If the excitation of the synchronous generator fails, it acts as a/an induction motor. synchronous motor. induction generator. synchronous generator. induction motor. synchronous motor. induction generator. synchronous generator. ANSWER DOWNLOAD EXAMIANS APP
EXAMIANS