Electrical Machines A 4 pole, 3-phase induction motor is running at 4% slip at full load. If the speed of the motor is 720 rpm, the supply frequency is 40 HZ 50 Hz 25 Hz 60 Hz 40 HZ 50 Hz 25 Hz 60 Hz ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The brush-axis of a bipolar dc motor is rotated by 90°. The effect of this rotation on the back emf Eband the torque developed Tdwould be such that both Eb and Td are unchanged Eb is unchanged, but Td is zero Eb is zero, but Td is unchanged both Eb and Td are zero both Eb and Td are unchanged Eb is unchanged, but Td is zero Eb is zero, but Td is unchanged both Eb and Td are zero ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Armature reaction depends on which of the following? power factor of load None of these both 1 and 2 magnitude of load current power factor of load None of these both 1 and 2 magnitude of load current ANSWER DOWNLOAD EXAMIANS APP
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 2, 4 1, 3 2, 3 1, 4 2, 4 1, 3 2, 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 3 - Φ induction motor draws an current of 50 A from mains when starts by direct switching. If an auto transformer with 60 % tapping is used for starting the current drawn from the mains will be 80. 36. 18. 50. 80. 36. 18. 50. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 2 pole synchronous machine is operating at 3000 rpm. Find the relation between electrical angular momentum (ωe) and mechanical angular momentum (ωm) ? ωe = 1/2*ωm ωe = 2*ωm ωe = 4*ωm ωe = ωm ωe = 1/2*ωm ωe = 2*ωm ωe = 4*ωm ωe = ωm ANSWER DOWNLOAD EXAMIANS APP
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