Electrical Engineering: Electrical Machine MCQ

36. Question

In a single phase transformer the total iron loss is 2500W at normal voltage of 440V and frequency 50Hz. The total iron loss is 850 W at 220V and 25Hz . Then at nominal voltage and frequecy, the hysteresis loss and eddy current loss respectively are     

37. Question

A three-phase balanced voltage is applied to the load shown. The phase sequence is RYB. the ratio  |IB| / |IR| is____

38. Question

An air-core radio- frequency transformer as shown has a primary winding and a secondary winding.The mutual inductance M between the winding of the transformer is_____μH.

39. Question

An 8-pole ,50hz .three-phase , slip-ring induction motor has an effective rotor resistance of 0.08Ω per phase. its speed at maximum torque is 650 RPM. The additional resistance per phase that must be inserted in the rotor to achieve maximum torque at start is ____Ω

neglect magnetising current and stator leakage impedance. Consider equivalent circuit parameter referred to stator.

40. Question

A single generator having a source resistance of 50Ω is set to generate a 1khz sinewave. Open circuit voltage is 10V peak tom peak. Connecting a capacitor across the terminals reduces hte voltage to 8V peak to peak. The value of this capacitor is ____μF.