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From: thomson@uthub.UUCP (Brian Thomson)
Newsgroups: net.consumers,net.analog
Subject: Re: power/energy meters
Message-ID: <202@uthub.UUCP>
Date: Wed, 27-Mar-85 16:48:12 EST
Article-I.D.: uthub.202
Posted: Wed Mar 27 16:48:12 1985
Date-Received: Fri, 29-Mar-85 14:15:11 EST
References: <1027@hound.UUCP>, <450@hou2b.UUCP> <844@homxa.UUCP>
Organization: CSRG, University of Toronto
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Xref: utai net.consumers:1434 net.analog:183

There seems to be a great deal of misinformation here.

1) The wattmeter on the side of your house does indeed measure
(and integrate) power, and will not overcharge you if you have
low power-factor loads.

2) Large industrial power users are also charged for true power, but
with a contractually-determined power factor penalty.  That is, the
user promises to maintain a power factor of .95 lagging or better, and
the power utility charges them an appropriately small penalty.  If the
user only promised .8 or better, the penalty would be greater.
Of course, the utility may conduct power factor spot-checks to be
sure you're holding up your end of the bargain.
They care about power factor because distribution losses are proportional
to current, not to power.
This is how it was explained to me one summer when I worked in a
substation in a nickel smelter in Manitoba.  One of my functions was
to monitor power factor and tell the electric furnace operators when
to add or remove capacitors.  We were a rather heavy power user - I
seem to recall that the wattmeters wouldn't register at anything below
about 5 megawatts.
-- 
		    Brian Thomson,	    CSRI Univ. of Toronto
		    {linus,ihnp4,uw-beaver,floyd,utzoo}!utcsrgv!uthub!thomson