Electrical Machines In a DC generator sparking between brushes and commutator surface may be due to too rapid reversal of current. over commutation. under commutation. any of the above. too rapid reversal of current. over commutation. under commutation. any of the above. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines When operating, two or more transformers in parallel, % impedance of these transformers should be same. proportionate to MVA rating of transformers. such that actual impedance of all transformers would be same. inversely proportional to MVA rating of transformers. same. proportionate to MVA rating of transformers. such that actual impedance of all transformers would be same. inversely proportional to MVA rating of transformers. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the efficiency when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%. 82.5% 78.5% 72.5% 67.5% 82.5% 78.5% 72.5% 67.5% 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
Electrical Machines The noise resulting from vibrations of lamination set by magnetic forces, is termed as boo. zoom. magnetostriction. hum. boo. zoom. magnetostriction. hum. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If input of a transformer is square wave the output will be square wave. pulsed wave. sine wave. triangular wave. square wave. pulsed wave. sine wave. triangular wave. ANSWER DOWNLOAD EXAMIANS APP
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