In many cases, the extra circuits everyone is describing are not Power Factor Controllers at all. I have one of the devices, and (wonder of wonders) it uses a PIC 16C54 !!!! Most appliances need more power to get started than to run, and most induction motors (even with capacitor start) have higher running torque than starting torque. For that reason, motors must be oversized to handle the increased load during start. These "oversized" motors waste energy during running. The little add-on controllers allow for full voltage during startup, and back it down to 85 - 95 during normal operation. This saves a significant amount of electricity. Of course, since we are dealing with AC, reducing the RMS voltage usually involves reducing the duty cycle. This is done with TRIACs. Some intelligence in the device is needed, because if the appliance requires more power, the controller must respond by providing 100% duty cycle. This load is determined by the relationship between voltage and current. If both are in phase (zero degrees phase shift), the motor is heavily loaded. As the motor's load drops off, the phase angle between voltage and current increases, and the controller reduces the motor voltage until the phase angle is again close to zero. The need for such intelligence is the reason a PIC is employed. The savings are roughly proportional to the amount of voltage reduction. I have such a controller on my refrigerator, and it backs the voltage down to about 90 volts during normal operation. It is interesting to note that when I have the door open, and the motor starts, the refrigerator door light gets brighter, and five or ten seconds later , the light gets dimmer. Also note: The electrical power meters on your house do NOT just measure current! They actually have voltage and current coils, and do a "magnetic multiply", thereby showing actual RMS watts (vector voltage X vector current) used. ----- Original Message ----- From: Peter Cousens To: Sent: Saturday, November 20, 1999 1:22 AM Subject: Re: [OT]Power Factor Correction > Herbert Graf wrote: > > > > > > the actually power meter that the electrical company reads slow down? I > > > > doubt it since I believe all meters ignore the effects of this sort of > > > > thing. I don't believe it would damage anything, but I don't > > > think it would > > > > reduce the amount of power the power company charges you for > > > using, I might > > > > be wrong though. TTYL > > > > > > My understanding's that the power company doesn't charge you for > > > REACTIVE loading, just real power you use, for regular consumers. > > > (Industrial users can get a discount for presenting a less inductive > > > load, but that's an entirely different bushel of worms!) I haven't > > > heard a whole lot of power experts comment positively on those. > > > > That's what I believe as well, can anybody confirm, I'd be interested in > > knowing if these are just the same devices I heard of before or if they are > > something new. TTYL > > The way I see it is that with a inductive or capacitive load the current > peak is not > at the voltage peak > > So as the consumer meter only measures current, you are getting less > power for your > money > ie: with a resistive load 10Amps x 120Volts = 1.2KW > with a reactive load 10Amps x 100Volts = 1KW > > I don't think it takes much to shift the peak current from 120V to 100V > in an industrial > enviroment but for a home the savings could be small > > I would say that savings could me made by putting a cap across the > fridge motor though. ! > IF YOU KNOW WHAT YOUR DOING > -- > Peter Cousens > email: p.cousens@cwcom.net or p.cousens@virgin.net > smail: 48, Yarmouth Cresent, London, N179PQ, England.