A 6 kV , 1000 kVA , 3-ph alternator is delivering full-load at 0.8 lagging. Its reactance is 20% and resistance negligible. By changing the excitation, the e.m.f. is increased by 25% at this load. Calculate the new current and power factor. The machine is connected to infinite bus-bars.

Q: 3. A three-phase 60 Hz Wye connected, 2,000-kVA, 2,300-V alternator give a short circuit-test…

A: The solution is given below

Q: What is the purpose of transformers in power distribution, and how do they work?

A: Transformers play a vital role in electrical power distribution systems, and their primary purpose…

Synchronous Motor

The synchronous motor is an AC electric type motor where at a steady-state the shaft rotation is synchronized with the supply current variable-frequency. To an integral number of AC cycles, the rotation period is exactly equal. The stator of the motor in the synchronous motor contains multi-phase AC electromagnets due to which a magnetic field is created that rotates in time with the oscillation of the line current. The rotor contains a permanent magnet and the rotor rotates in synchronization with the stator field at the same rate and provides the second synchronized magnetic field which is rotating in nature as a result. When the synchronous motor is supplied with independently excited multi-phase AC electromagnets on both the rotor and the stator, it is termed as a doubly-fed machine. The most widely used AC-type motors are the synchronous AC motor and the induction AC motors.