Question

Question: The equivalent circuit parameters of a 440 V, 3-phase, 8-poles, and 50 Hz star connected motor are given below. The short-circuit test is conducted with a locked rotor and a line current of 80 A. The open-circuit test is conducted by supplying the stator winding at rated voltage and at the same time driving the rotor in the same direction as the rotating field, at synchronous speed; s=0.

R₁ = 0.1, X₁ = 0.5, R^I₂ = 0.1, X^I₂ = 0.5, X_m = 20, Rm = 100 in all ohms

Determine:

a) The line voltage and power factor on the short-circuit test;

b) The line current and power factor on the open-circuit test;    

c) The equivalent circuit per-phase if these tests were analysed on an approximate basis                                                           

d) The motor efficiency, speed regulation and full load torque when this motor is running at 720 rpm. Use approximate equivalent circuit and ignoring no load current.