Electrical Machine MCQs

Two parallel connected, three-phase, 50Hz ,11kV,star-connected synchronous machines A and B, are operating as synchronous condensers. They together supply 50 MVAR to a 11kV grid. Current supplied by both the machines are equal. Synchronous reactance of machine A and machine B are 1Ω and 3Ω, respectively. Assuming the magnetic circuit to be linear, the ratio of excitation current of machine A to that of machine B is 

a three-phase,50Hz,star-connected cylindrical-rotor synchronous machine is running as a motor. Ωthe machine is operated from a 6.6 kV grid and draws current at unity power factor. The synchronous reactance of the motor is 30 Ω per phase. The old angle is 30°. The power delivered to the motor in kW is 

A 375W,230V, 50Hz, capacitor start single phase induction motor has the following constants for the main auxiliary winding ( at starting): Zm = ( 12.50+ j 15.75)Ω (main winding), Za =(24.50+ j12.75)Ω (auxiliary winding). Neglecting the magnetizing branch, the value of the capacitance to be added in series with the auxiliary winding to obtain maximum torque at starting is 

A 4 pole induction machine is working as an induction generator. The generator supply frequency is 60Hz. The rotor current frequency is 5Hz. The mechanical speed of the rotor in RPM is

A solid iron is placed in a region containing a uniform magnetic field such that the cylinder axis is parallel to the magnetic field direction. The magnetic field lines inside the cylinder will