Synchronous induction motor

  • Engineering
  • Thread starter zsolt2
  • Start date
  • #1
20
2

Homework Statement


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.


Homework Equations


Voltage /phase:415 x Sqr3 =240 V
IXs= 10 x 5 = 50V[/B]



The Attempt at a Solution


i,
E^2=240^2 x 50^2=245V
cosσ=240/245=0.979 (σ=load angle)
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)[/B]
 

Answers and Replies

  • #2
NascentOxygen
Staff Emeritus
Science Advisor
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1,073
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
20
2
Hi.
Yes I think I have solved it
P.f.=0.89
I= 11.24
If I am right
Thank you
 
  • #4
1
0
Hi.
Yes I think I have solved it
P.f.=0.89
I= 11.24
If I am right
Thank you
Love to know how you got that
 
  • #5
486
130
The result is correct but I would like to know how you arrived at this result.
 

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