AC Machines — Winter 2023

Derive emf equation of an alternator.

Compare squirrel cage and slip ring Induction Motor.

Explain the parallel operation of two alternators.

Discuss the methods of starting of synchronous motor.

Describe the effect of armature reaction with zero lagging power factor in case of a synchronous generator

Explain the torque slip characteristics of a three-phase induction motor and describe the significance of stable and unstable region

List the methods of determination of voltage regulation of an alternator. Describe any one of them in detail.

Athree phase 400/200V, Y-Yconnected wound rotor has 0.06 Ω rotor resistance and 0.3 Ω standstill reactance per phase. Find the additional resistance required in the rotor circuit to make the starting torque equal to the maximum torque of the rotor.

Discuss the procedure to perform no load and blocked rotor tests on a three- phase induction motor.

Draw the phasor diagram (vector diagram) for a three-phase induction motor and justify the statement „Power factor of the motor improves from no load to full load‟.

Define and explain pitch factor and distribution factor with respect to an alternator.

Explain any one method to find the voltage regulation of an alternator

What is synchronization? Explain two bright one dark lamp method of synchronization.

Explain with reason why synchronous motor is not self-starting.

Discuss the methods of starting of synchronous motor.

A 3-phase, 16-pole alternator has the following data: Number of slots = 192; Conductors / slot = 8 (conductors of each phase are connected in series) coil span = 160 electrical degrees, speed of the alternator = 375 rpm; flux/pole = 55m Wb. Calculate the phase and line voltages. speed of the alternator = 375 rpm.; flux/pole = 55m Wb. Calculate the phase and line voltages.

What is hunting? How to minimize it?

Explain working principle of Induction Generator.

List the different methods for speed control of an Induction motor and explain any two in detail with necessary diagram.1

Briefly explain the double field revolving theory in relation to single phase AC motors.

Explain the construction and working of universal motor.

Explain V-curves and its importance for synchronous motor.

Briefly explain the role of capacitor in the ceiling fan.

Explain slip test for measurement of direct and quadrature axis reactances for salient pole machine

Draw the schematic diagram and explain the construction and working of shaded pole single phase motor.