Question

If the synchronous machine is connected to an infinite bus of constant voltage Vt, through a transformed, a transmission line of reactance ‘X’. Then power for a cylindrical machine is?

(a) P = (Ef*Vt sinδ)/(Xs + X)

(b) P = (Ef*Ef sin2δ)/(Xs + X)

(c) P = (Ef*Vt sinδ)/(Xs – X)

(d) P = (Vt*Vt sinδ)/(Xs + X)

The question was posed to me during a job interview.

Question is taken from Power Angle Characteristics of Synchronous Machines in portion Synchronous Machines of Electrical Machines

Answer 1

Right option is (a) P = (Ef*Vt sinδ)/(Xs + X)

The explanation is: The total reactance will be the reactance offered to the synchronous motor in the machine.