Question

For a 3 phase 400V alternator having 0.5pu of synchronous reactance and its excitation voltage of 1.2pu and Vt of 1pu. Then the power delivered to the infinite bus is?

(a) 2.4pu

(b) 4.8pu

(c) 1.44pu

(d) 1pu

I had been asked this question in an internship interview.

My question comes from Power Angle Characteristics of Synchronous Machines in section Synchronous Machines of Electrical Machines

Answer 1

Right answer is (a) 2.4pu

The explanation is: P = EV/X = 1.2*1/0.5 = 2.4 pu.