Electrical Machines Which of the following is/are the advantages of carbon brush over the copper brush? In case of any sparking they will be less damaged than copper brushes They are not hard as copper brush They are self lubricating in nature All of these In case of any sparking they will be less damaged than copper brushes They are not hard as copper brush They are self lubricating in nature All of these ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In induction motor the 7th harmonic torque may make the motor rotate at (1 / 7)th synchronous speed. This is called harmonics. cogging. crawling. resonance. harmonics. cogging. crawling. resonance. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 400 V, 50 Hz, 30 Hp, three phase IM is drawing 50 A current at 0.8 p.f lagging. The stator and rotor copper losses are 1.5 KW and 900 W respectively. The friction and windage losses are 1050 W and core losses are 1200 W. The air gap power of the motor will be 26.21 kW. 25 kW. 24.11 kW. 23.06 kW. 26.21 kW. 25 kW. 24.11 kW. 23.06 kW. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines An electric motor with constant output power will have a torque speed characteristics in the form of a Circle about the origin. Straight line parallel to the speed axis. Rectangular hyperbola Straight line through the origin. Circle about the origin. Straight line parallel to the speed axis. Rectangular hyperbola Straight line through the origin. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A commutator in DC machines can 1. provide half-wave rectification 2. Provide full-wave rectification 3. convert ac to dc 4. Convert dc to ac 5. provide controlled full-wave rectification From these, the correct answer is 2, 3, 4, 5 2, 3 ,5 2, 3, 4 1, 2, 3 2, 3, 4, 5 2, 3 ,5 2, 3, 4 1, 2, 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines To have sparkless commutation, the armature reaction effect in a DC machine is neutralized by fixing the brush axis inline with the pole axis. increasing field excitation. compensating winding and commutating poles. shifting the brush axis from GNA to MNA. fixing the brush axis inline with the pole axis. increasing field excitation. compensating winding and commutating poles. shifting the brush axis from GNA to MNA. ANSWER DOWNLOAD EXAMIANS APP
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