Synchronous motor, angles

Thread Starter

IbrahimF

Joined Jul 21, 2017
25
Hello I currently have a question which I am currently stuck on. I basically need to know the relationship between current phase angle and the torque angle.
here is the question
The synchronous motor of exercise E3 has a synchronous reactance of 5.0  per phase. (a) If the motor operates at full load with a torque angle of 45º and unity power factor, determine:
a) the phase voltage,
 the excitation voltage,
 the line current,
 the output power,
 the developed torque.
(b) If the excitation voltage is unchanged and the load on the motor is increased until the limit of stability is reached, determine:
 the line current,
 the power factor.
 the output power,
 the developed torque.

Here is excerise E3
A non-salient star-connected 2-pole 3-phase synchronous motor operates from a 50 Hz supply with a line voltage of 400 V. The line current is 46.2 A, and the power factor is 1.0. Mechanical losses and the armature resistance may be neglected. Determine: (a) the electrical input power, (b) the synchronous speed in rad/s, (c) the developed torque.


I made the two formulas equal to each to get I . the values I used is 231 for V
E=327V
Xs= 5 ohms
and Ws= 314 rad/s
the torque angle  is 90
and the phase angle I am using is 0. I think that's where I am wrong
How can I get the phase angle is there a relationship?

Thanks

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