Electrical Machines The 3 - Φ induction motors are, by a very considerable margin, the most widely used AC motors as they are capable of operation under range of leading and lagging pf. they have maximum efficiency and maximum starting torque. these are cheaper in cost, simple and rugged in construction. they have very good speed regulation. they are capable of operation under range of leading and lagging pf. they have maximum efficiency and maximum starting torque. these are cheaper in cost, simple and rugged in construction. they have very good speed regulation. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 220 ,V 15 , kW 100 rpm shunt motor with armature resistance of 0.25 , W has a rated line current of 68 A and a rated field current of 2.2 A. The change in field flux required to obtain a speed of 1600 rpm while drawing a line current of 52.8 A and a field current of 1.8 A is 36.36% decrease 36.36% increase 36.36% increase 18.18% increase 36.36% decrease 36.36% increase 36.36% increase 18.18% increase ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The frequency of voltage generated by an alternator having 8 poles and rotating at 250 rpm is 50 Hz. 60 Hz. 25 Hz. 16.67 Hz. 50 Hz. 60 Hz. 25 Hz. 16.67 Hz. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A voltmeter gives 120 oscillations per minute when connected to the rotor of an induction motor. The frequency is 50Hz. The slip of the motor is 5% 4% 25% 2% 5% 4% 25% 2% 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%. 67.5% 72.5% 78.5% 82.5% 67.5% 72.5% 78.5% 82.5% ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a synchronous motor hunting can be reduced to minimum possible by using a flywheel. providing damper winding in the rotor pole faces. designing the motor for adequate synchronizing power. any of above methods. using a flywheel. providing damper winding in the rotor pole faces. designing the motor for adequate synchronizing power. any of above methods. ANSWER DOWNLOAD EXAMIANS APP
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