Electrical Machines Oil is provided in an oil filled transformer for insulating. cooling. both cooling and insulation. lubrication. insulating. cooling. both cooling and insulation. lubrication. 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, 4, 5, 6 1, 2, 5 2, 3, 6 3, 4, 5 2, 4, 5, 6 1, 2, 5 2, 3, 6 3, 4, 5 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The functions of inter poles are nullify reactance voltage and improve the commutation. reduce cross magnetization effect and improve commutation None of these both 1 and 2 nullify reactance voltage and improve the commutation. reduce cross magnetization effect and improve commutation None of these both 1 and 2 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A large series motor is never started without some mechanical load on it because otherwise it will open fuse or circuit breaker. develop excessive speed and damage itself. produce sparking at brushes. draw too much current. open fuse or circuit breaker. develop excessive speed and damage itself. produce sparking at brushes. draw too much current. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Neglecting all losses, the developed torque (T) of DC separately excited motor, operating under constant terminal voltage is reduced to its output power (P) as T ∝ √P. T ∝ P. T is independent of P. T2 ∝ P3. T ∝ √P. T ∝ P. T is independent of P. T2 ∝ P3. 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, 3, 5 1, 2, 5 1, 2, 3, 4 2, 3, 4 1, 3, 5 1, 2, 5 1, 2, 3, 4 ANSWER DOWNLOAD EXAMIANS APP
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