Electrical Machines The armature mmf in a dc machine is 1. stationary with respect to field poles 2. stationary with respect to armature 3. rotating with respect to field poles 4. rotating with respect to armature From these, the correct answer is 1, 4 1, 3 2, 4 2, 3 1, 4 1, 3 2, 4 2, 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In DC machine, the armature windings are placed on the rotor because of necessity for commutation. generation of voltage. electromechanical energy conversion. development of torque. commutation. generation of voltage. electromechanical energy conversion. development of torque. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The introduction of interpoles in between the main poles improves the performance of a dc machine, because a counter-emf is induced in the coil undergoing commutation the flux waveform is improved with reduction in harmonics the interpoles produce additional flux to augment the developed torque the inequality of air-gap flux on the top and bottom halves of the armature is removed a counter-emf is induced in the coil undergoing commutation the flux waveform is improved with reduction in harmonics the interpoles produce additional flux to augment the developed torque the inequality of air-gap flux on the top and bottom halves of the armature is removed ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 4 pole DC generator runs at 750 rpm and generate an emf of 240 V. The armature is wave wound and has 792 conductors. If the total flux from each pole is 0.0145 Wb. What is the leakage co-efficient? 1.2. 1.5. 1.4. 1.8. 1.2. 1.5. 1.4. 1.8. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines To eliminate the 5th harmonic in the induced voltages their respective pitch factor angle should be 30° 36° 72° 18° 30° 36° 72° 18° ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The field system of an alternator is usually excited 3 - Φ, 50 Hz and 400 V. 110 / 220 V AC. 250 / 250 V DC. 230 V AC. 3 - Φ, 50 Hz and 400 V. 110 / 220 V AC. 250 / 250 V DC. 230 V AC. ANSWER DOWNLOAD EXAMIANS APP
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