Finding Actual Power

[SonobondRay]

I'm looking for a VI that will calculate the actual power from my voltage and current signals. Basically my real problem is that I can't fully acquire the Phase difference as a function time, and because of this I can not calculate the actual power.
Just so that we are on the same page, I should mention that I'm looking at two sign waves but there frequencies are different so my phase difference is not constant. If someone can please point in the direction of VI or combination of VI's that will either calculate "Actual" Power or the Phase difference as a f(time), I would really appreicate it.

[DOC-doc]

To calculate the phase difference you can compute the product of the two signals I and V. You will have a signal composed of twice the frequency + the phase difference.

To get only the phase difference, use a low pass filter to remove the high fre part of your data

Doc-Doc

[unclebump]

I'm not sure what power level you are measuring. I use devices from this company for 480VAC motors. They also have products for DC applications. http://www.loadcontrols.com/