Hi, I have a feeling this has been posted before, but it doesn't show in my current postings, as don't the FAQs. Anyway, here goes:
Can anyone give me an idea on the stability to be expected in determining the power input to a 3 phase induction motor from a current measurement of one phase, appropriately linearised and calibrated. Ie. the current measurement is logged against the output of an accurate, temporarily installed polyphase power meter at several working points, then the curve between the current test points is interpolated and used to provide an ongoing measurement of power. Assume the CT is accurate and the supply voltage steady. I'm after variable factors within the drive that would affect the relationship, and by how much.
Drives are 3.3KV 500KW, standard squirrel cage induction. Incidentally, to hopefully prevent spurious responses, this relates to a real industrial problem, not homework. TIA