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 an AC source. to a DC source. in reverse. to earth. to an AC source. to a DC source. 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 2, 3, 6 2, 4, 5, 6 1, 2, 5 3, 4, 5 2, 3, 6 2, 4, 5, 6 1, 2, 5 3, 4, 5 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following is/are the methods to reduce the armature reaction and its effects? All of these pole chamfering compensating winding pole stacking All of these pole chamfering compensating winding pole stacking ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines φA DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the speed when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%. 940 RPM 960 RPM 970 RPM 920 RPM 940 RPM 960 RPM 970 RPM 920 RPM ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines What is the reason for stationary armature essential in alternators above 5 KVA? Insulation requirement is less. Operating cost is less. All of these Collecting of large current is simple. Insulation requirement is less. Operating cost is less. All of these Collecting of large current is simple. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines An induction motor is, in general analogous to auto transformer. two winding transformer with secondary short circuited. None of these two winding transformer with secondary open circuited. auto transformer. two winding transformer with secondary short circuited. None of these two winding transformer with secondary open circuited. ANSWER DOWNLOAD EXAMIANS APP
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