Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!usc!apple!portal!cup.portal.com!dbell
From: dbell@cup.portal.com (David J Bell)
Newsgroups: sci.electronics
Subject: Re: Need to buy or build 3-phase recording kW meter
Message-ID: <39890@cup.portal.com>
Date: 6 Mar 91 05:42:35 GMT
References: <1991Mar5.161244.503@phri.nyu.edu>
Distribution: na
Organization: The Portal System (TM)
Lines: 21


>	The building I live in (a 54 unit residential cooperative) is
>getting whomped by peak usage charges on our electric bill (last month was
>$650 in kWh charges and $350 in peak usage).  Our peak last month was 18.0
>kW (our average was about half that).  I have been given the task of trying
>to figure out how to cut our electric bill.

Roy, I can't add too much to what Dave Lesher already posted, but you 
could pursue your idea of a high-speed A/D in a PC. Keep in mind that you
have to sample fast enough to make essentially simultaneous readings
of voltage and current on all three phases. The best way to achieve this
is to have six sample-and-hold amplifiers feeding into the A/D in
sequence, with the S&H's triggered at the same time...

On another subject, did I understand you correctly, that you are
"getting whomped" for about $1000 a month for *54 UNITS*??? TOTAL???
In New York???  In WINTER??????  I just paid $379 for last month
for four people (one a baby) in a single house!! In California!!!
I wish I had your problem (proportionally, of course)!  :{)

Dave