Electrical Machines Which type of motors are preferred in lifts? DC series motors. None of these DC shunt motors. DC compound motors. DC series motors. None of these DC shunt motors. DC compound motors. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines On switching a DC motor to DC supply mains, it is found to rotate in the direction opposite to that for which it is designed. The DC motor is Differentical compound. Cummulative compound. Series shunt. have an equal number of electrons and protons. Differentical compound. Cummulative compound. Series shunt. have an equal number of electrons and protons. 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 to a DC source. to an AC source. in reverse. to earth. to a DC source. to an AC source. in reverse. to earth. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The counter (or back) emf in a dc machine is 1. the same as generated emf in a dc motor 2. proportional to field flux and armature speed 3. not the same as generated emf in a dc motor 4.inversely proportional to field flux 5. proportional to number of armature conductors 6. constant from no load to full load From these, the correct answer is 3, 4, 5 2, 3, 6 2, 4, 5, 6 1, 2, 5 3, 4, 5 2, 3, 6 2, 4, 5, 6 1, 2, 5 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 2, 3, 4, 5 2, 3, 4 1, 2, 3, 4 and 5 1, 3, 4, 5 2, 3, 4, 5 2, 3, 4 1, 2, 3, 4 and 5 1, 3, 4, 5 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The mmf produced by rotor currents of a 3 - Φ induction motor rotates at the speed of rotor in the air gap. rotates at synchronous speed with respect to rotor. is at standstill with respect to stator mmf. rotates at slip speed with respect to stator mmf. rotates at the speed of rotor in the air gap. rotates at synchronous speed with respect to rotor. is at standstill with respect to stator mmf. rotates at slip speed with respect to stator mmf. ANSWER DOWNLOAD EXAMIANS APP
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