# Synchronous induction motor

1. Oct 23, 2016

### zsolt2

1. The problem statement, all variables and given/known data
A star-connected, three-phase synchronous induction motor takes a current of 10 amps from a 415 volt supply at unity power factor when supplying a steady load. If the synchronous reactance is 5 ohms/phase and the resistance is negligible, draw the phasor diagram and calculate the value of the generated emf and the load angle.
(ii) If the excitation is reduced by 10% and, as a consequence the generated e.m.f. is reduced by 10%, calculate the new value of the generated e.m.f E, the stator current, the power factor and the load angle, assuming that the load does not change.

2. Relevant equations
Voltage /phase:415 x Sqr3 =240 V
IXs= 10 x 5 = 50V

3. The attempt at a solution
i,
E^2=240^2 x 50^2=245V
σ=11.76°

ii,
E= 245-92454 x 0.1 =220.5
My problem is how to calculate the current and the power factor as I=P/(√3 x V x I x power factor)

2. Oct 23, 2016

### Staff: Mentor

Hi zsolt2. I see that you have ticked to mark this thread as SOLVED.

Does this mean you have been able to answer the question, so don't need further help from anyone here?

3. Oct 23, 2016

### zsolt2

Hi.
Yes I think I have solved it
P.f.=0.89
I= 11.24
If I am right
Thank you