Electrical Machines A self-excited shunt generator fails to build up, because 1. the field circuit is open 2. The armature circuit is open 3. the residual magnetism is absent 4. The direction of rotation is wrong From these, the correct answer is 1, 2 and 3 1, 2, 3 and 4 3 only 1, 3 1, 2 and 3 1, 2, 3 and 4 3 only 1, 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The following statements relate to compensating winding (CW) and interpole winding (IW) of a dc machine : 1. CW neutralizes the armature reaction under a pole pitch 2. IW is connected in series with armature circuit 3. IW produces mmf in the commutating zone only 4. CWmmf is directed along the brush axis 5. Mmf produced by IW is equal to armature mmf From these, the correct statements are 1, 2, 3, 4 and 5 1, 3, 4, 5 2, 3, 4 2, 3, 4, 5 1, 2, 3, 4 and 5 1, 3, 4, 5 2, 3, 4 2, 3, 4, 5 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In case the conditions for maximum power for DC motor are established, the efficiency of the motor will be Any where between 75 % and 90 %. Less than 50 % Around 90 % Around 100 %. Any where between 75 % and 90 %. Less than 50 % Around 90 % Around 100 %. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A separately-excited DC generator, running at rated speed, has 6 volts across its armature terminals with no field current. When field winding is excited with one ampere, the voltage builds up to 250 V at no load. In case field current is reduced to zero, with the speed remaining unaltered, the armature terminal voltage would be less than 6 V zero 6 V more than 6 V less than 6 V zero 6 V more than 6 V ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines To get the speed of DC motor is more than normal without wastage of electrical energy _____________ is used. None of above. Rheostatic control. Ward Leonard control. Any of above method. None of above. Rheostatic control. Ward Leonard control. Any of above method. 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 deteriorate and the speed falls. deteriorate and the speed rises. improve and the speed falls. improve and the speed rises. deteriorate and the speed falls. deteriorate and the speed rises. improve and the speed falls. improve and the speed rises. ANSWER DOWNLOAD EXAMIANS APP
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