Electrical Machines Winding conductors of an electrical power transformer are mainly insulated by cotton insulation. paper insulation. rubber insulation. wooden insulation. cotton insulation. paper insulation. rubber insulation. wooden insulation. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following factors improve commutation in a dc machine ? 1. High contact resistance of brushes 2. High inductance of the coils undergoing commutation 3. Shifting of brushes in the direction of rotation for a generator and in the opposite direction For a motor 4. Narrow width for the commutation bars Select the correct answer using the codes given below : Codes : 1, 2 and 4 1 and 3 2, 3 and 4 1, 2, and 3 1, 2 and 4 1 and 3 2, 3 and 4 1, 2, and 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 4 pole 50 Hz 1-phase induction motor is running at 1470 rpm. Find the forward and backward slips? 0.02, 0.98 0.02, 1.98 0.04, 0.96 0.04, 1.96 0.02, 0.98 0.02, 1.98 0.04, 0.96 0.04, 1.96 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In case of 3 - Φ IM, plugging means interchanging two supply phases for quick stopping. starting the motor on load which is more than the rated load. pulling the motor directly on line without a rotor. locking of rotor due to harmonics. interchanging two supply phases for quick stopping. starting the motor on load which is more than the rated load. pulling the motor directly on line without a rotor. locking of rotor due to harmonics. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In speed control of DC Series motor, speed lower than the rated speed can be obtained by Connecting an additional resistance in the armature circuit. Any of the above. Connecting an additional resistance in the field circuit. Connecting an additional resistance in stator circuit. Connecting an additional resistance in the armature circuit. Any of the above. Connecting an additional resistance in the field circuit. Connecting an additional resistance in stator circuit. 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 1, 2, 5 3, 4, 5 2, 4, 5, 6 2, 3, 6 1, 2, 5 3, 4, 5 2, 4, 5, 6 2, 3, 6 ANSWER DOWNLOAD EXAMIANS APP
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