Electrical Machines The sparking at the the brushes, in a DC machines is due to presence of commutator. armature reaction. reactance voltage. high resistance of carbon brushes. presence of commutator. armature reaction. reactance voltage. high resistance of carbon brushes. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a 3 - Φ IM with line frequency f1 and winding factor kw1 and kw2 for stator and rotor respectively the ratio of per phase stator winding emf E1 to per phase rotor winding emf E2 at standstill is given by E1 / E2 = 1. E1 / E2 = N1kw1 / N2kw2. E1 / E2 = N1 / N2. E1 / E2 = f1kw1 / f2kw2. E1 / E2 = 1. E1 / E2 = N1kw1 / N2kw2. E1 / E2 = N1 / N2. E1 / E2 = f1kw1 / f2kw2. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The supply voltage to an induction motor is reduced by 10%. By what percentage, approximately, will the maximum torque decrease? 40% 19% 10% 5% 40% 19% 10% 5% ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The direction of generated emf in the armature coil of a DC machine is 1. the same as that of the current in a generator 2. the same as that of the current in a motor 3. opposite to that of the current in a generator 4. opposite to that of the current in a motor From these, the correct answer is 2, 3 1, 4 1, 3 2, 4 2, 3 1, 4 1, 3 2, 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In synchronous motor the torque is proportional to 1/P² P² Power P 1/P 1/P² P² Power P 1/P ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Satisfactory commutation of DC machine requires brushes should smoothly run in the holders. smooth, concentric commutator properly undercut. All of these brushes should be of proper grade and size. brushes should smoothly run in the holders. smooth, concentric commutator properly undercut. All of these brushes should be of proper grade and size. ANSWER DOWNLOAD EXAMIANS APP
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