rockman7892
Electrical
- Apr 7, 2008
- 1,171
I am looking at a Multilin 750 relay and PQMII meter and trying to corrolate the power factor on each to the respecitve voltage and current phasors. With a power factor of .70 I expected to see the current phasor lag the voltage phasor by 45 degrees. However when I looked I saw Vab at 0 degrees and Ia at 80 degrees as an example.
When wondering why I saw 80 degrees instead of the 45 I expected I called Multilin and they explained to me that it was because the power factor was taken with respect to Van and therefore presented a 30 degree shift. By adding this 30 degree shift to my expected 45 degree angle I come up with 75 degrees which is close to the angle which I am seeing.
Why is the power factor calculated off of the L-N volage as opposed to the L-L voltage. Where does this 30 degree shift come from? Does is come from subtraction of Va-Vb? I have a wye LRG system so do not carry a nuetral into these relays. How is the neutral then calculated or derived.
I would appreciate any explanations or examples.