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, 3 and 4 1, 2 and 3 1, 3 3 only 1, 2, 3 and 4 1, 2 and 3 1, 3 3 only ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines For the speed control of polyphase squirrel cage induction motor, if frequency of operation is decreased with constant V, Tst increases None of these either of these constant supply voltage V, starting torque Tst decreases constant V, Tst increases None of these either of these constant supply voltage V, starting torque Tst decreases ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a DC machine the armature mmf is stationary with respect to field poles. rotating with respect to field poles as well as armature. rotating with respect to field poles. stationary with respect to armature. stationary with respect to field poles. rotating with respect to field poles as well as armature. rotating with respect to field poles. stationary with respect to armature. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines φA 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 speed when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%. 920 RPM 960 RPM 940 RPM 970 RPM 920 RPM 960 RPM 940 RPM 970 RPM ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The armature mmf of a DC machine has triangular space distribution and rotates at the speed of armature. trapezoidal space distribution and is stationary in space. triangular space distribution and is stationary in space. stepped distribution and rotates at the speed of armature. triangular space distribution and rotates at the speed of armature. trapezoidal space distribution and is stationary in space. triangular space distribution and is stationary in space. stepped distribution and rotates at the speed of armature. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Under operating conditions the rotor conductor should be _________________ in induction motor. always closed. semi closed or semi opened. always opened. none. always closed. semi closed or semi opened. always opened. none. ANSWER DOWNLOAD EXAMIANS APP
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