Electrical Machines A self-excited shunt generator fails to build up, because 1. the field circuit is open 2. The armature circuit is open 3. the residual magnetism is absent 4. The direction of rotation is wrong From these, the correct answer is 1, 2 and 3 1, 2, 3 and 4 3 only 1, 3 1, 2 and 3 1, 2, 3 and 4 3 only 1, 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Armature flux is.............with respect to main field flux or main field poles? None of these rotates opposite direction stationary rotates same direction None of these rotates opposite direction stationary rotates same direction ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A DC Shunt Motor having shunt field resistance of 250 Ω and armature resistance of 0.5 Ω is connected to 250 V supply and load current of 21 A. What is the back emf generated ? 240 V. 210 V 230 V. 150 V. 240 V. 210 V 230 V. 150 V. 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 inequality of air-gap flux on the top and bottom halves of the armature is removed the flux waveform is improved with reduction in harmonics the interpoles produce additional flux to augment the developed torque a counter-emf is induced in the coil undergoing commutation the inequality of air-gap flux on the top and bottom halves of the armature is removed the flux waveform is improved with reduction in harmonics the interpoles produce additional flux to augment the developed torque ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The armature of DC machine is made of silicon steel lamination to reduce hysteresis loss only. reduce both eddy current and hysteresis loss. increase the permeability. reduce eddy current loss only. reduce hysteresis loss only. reduce both eddy current and hysteresis loss. increase the permeability. reduce eddy current loss only. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A slip ring Induction motor runs at 290 rpm at full load, when connected to 50 Hz supply. Determine the number of poles and slip. P = 40, s = 5.79 %. P = 50, s = 4.43 %. P = 20, s = 3.33 %. P = 60, s = 0.96 %. P = 40, s = 5.79 %. P = 50, s = 4.43 %. P = 20, s = 3.33 %. P = 60, s = 0.96 %. ANSWER DOWNLOAD EXAMIANS APP
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