I was under the impression that power factor losses could add up quite significantly for industrial type installations. The power companies here (Central USA) mandate that industrial installations are power-factor corrected. Home users don't have to bother with it, and can apparently "cheat" the power company of electricity if they run certain loads. (???) Robert B. -------------------------------------------- Robert B. email: robertb@nerdulator.net www.christmascheese.com - Great holiday gifts! ----- Original Message ----- From: "Lawrence Lile" To: "Microcontroller discussion list - Public." Sent: Tuesday, December 21, 2004 11:26 AM Subject: RE: [EE:] Energy savers such as this for real? > > They are NOT new. There ARE commercial units that do this same thing > > for air compressors and other high-power motors. They are usually called > > "phase correction" modules. The actual gain is negligible for a > > homeowner; > > you'd probably NEVER get your investment back. > > > > Usually, when something is too good to be true, it isn't. > > The gain and payback for a commercial outfit may be marginal as well. > > Back in the 1980's I looked into a company that was selling power factor correction equipment for commercial installations. They would go into a facility like a hospital or a factory, and put on a big show telling them that this magic black box would save them energy. They would install a power factor correction capacitor on the service entrance. > > A year later, when the bills did not go down, the client would call them complaining, and they would do a "study". The "study" would show that the usage actually went up 10%, but the power factor correction equipment was saving 10% so that is why the bills didn't change. Typical payback periods were quoted in months. > > I pulled out the IEEE references and did the real calculations for power factor correction in some of these facilities. I would come up with numbers like a savings of 0.01% and a payback period of 1500 years. The principle is, if the facility has a low power factor, increasing the PF can reduce I2R losses in the feeder cable. The effect is small, but real. > > I had a chance to examine the software this outfit used in these "studies". The way it calculated savings from PFC on the service entrance was to add up the utility bills for a year, and multiply the result by 10%. Olin, please have a field day with this calculation method if you will, I would love to hear your reaction to their "physics". > > This outfit was called ETI, Electenergy Technologies. They are still around, and still selling snake oil. Today their power factor correction junk is called "electroflow" and saves, not 10%, but 34%!. Google on it if you want to read more gibberish. > > -- Lawrence Lile, P.E. > Electrical and Electronic Solutions > Project Solutions Companies > www.projsolco.com > > --- > Outgoing mail is certified Virus Free. > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.762 / Virus Database: 510 - Release Date: 9/13/2004 > > > _______________________________________________ > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > > _______________________________________________ http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist