In article , Ted Edwards says...

measure the time between zero crossings of the waveforms, dT. Then
angle=360*dT/16.7msec and we know V, I and angle. So
P=V x I x Cos(angle).

Right, my point was that if he's measuring the phase
angle of a 120 volt waveform, but the compressor
is running on 240, he needs to plug the 240 number
into your calculation above. Not the 120.

Jim

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