3 phase induction motor

Prove :
average power = instantaneous power
in 3 phase induction motor

Questions by Yasser Ali   answers by Yasser Ali

Showing Answers 1 - 6 of 6 Answers

We can define the 3-phase voltages as:

1) v1 = Vp x sin(u);
2) v2 = Vp x sin(u +120);
3) v3 = Vp x sin(u -120)
4) vn^2 = v1^2 + v2^2 +v3^2 = K
5) sin(u +/- v) = sin(u)cos(v) +/- cos(u)sin(v);
6) sin^2(u) + cos^2(u) = 1
7) vn^2 = sin^2(u) + sin^2(u)cos^2(120) + cos^2(u)sin^2(120) + sin^2(u)cos^2(-120) + cos^2(u)sin^2(-120)
= sin^2(u) + sin^2(u)(0.25) + cos^2(u)(0.75) + sin^2(u)(0.25) + cos^2(u)(0.75)
= 1.5( sin^2(u) + cos^2(u)) = 1.5

I got the anwser from someone else. I still have to check his work! He looks smart doesnt he. No but thank you for asking this question I am intrested in better understanding how this works.

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