Does anyone know whether residential power meters measure real power or apparent power (vector sum of real and reactive power).
I have found claims for each on the web, so I am really only interested if you can give a pointer to some authoritative document such as a utilities commission decision, a statement by a utility, or a spec for residential meters.
They measure real power. You can Google for "electrodynamometer power meters."
I was told "Real Power" when I inquired, but looking at my electric bill lately, I'm guessing "Assumed Power" or "Line Our Pockets Power" :p Just kidding. Real Power seems to be the response I get.
tom @
For the most part they measure real power at residences, but I've heard tell of some areas in the southwestern USA where VAR metering is in use for homes because of the heavy usage of air conditioning equipment.
Jeff
A KWH meter?
They used to measure resistive load only.
That meant an appropriate capacitance across a reactive load (such as an AC compressor) could nullify the measured load. Still that way in most cases.
Why would AC screw up the PF? A loaded motor will have a PF pretty close to unity.
If that were always the case, then why would so many industrial operations invest in power factor correction systems?
Jeff
Because they have a lot of strange things like fluorescent lights? Computers?
Large industrial customers have the PF monitored and there's a substantial surcharge for the PF being too low. Electrical devices intended for home and commercial use are required to have PF correction built into them. All bets are off with industrial devices.
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