Re: Now the Bay Area rolling blackouts begin...

From: Michael S. Lorrey (
Date: Thu Jan 18 2001 - 12:35:04 MST

Chuck Kuecker wrote:
> At 09:15 AM 1/18/01 -0500, you wrote:
> >Some generators will put out 12 VAC, which then is stepped up to 120 VAC
> >by a transformer. Depending on the quality of its materials and design,
> >its output (due to CEMF and load power factor, harmonics, etc) could or
> >could not resemble a sine wave.
> There are kits available to "convert" the alternator in your car or truck
> to 120 VAC - is this what you mean? These of course would be outputting a
> couple of kilohertz AC - not exactly "clean" by 60 Hz standards...
> Any time you throw a transformer into the circuit, you have the possibility
> of saturation if you try to draw too much power. That will definitely cause
> distortion.
> What's CEMF? Counter "EMF"?

Yes, its the equivalent of resistance for inductors and transformers,
only the resistance is 90 degrees out of phase (typically), which is
where the power factor comes from. A transformer with a 1.0 power factor
will show peak load at 90 degrees out of phase from the voltage peak and
the load will be 1.414 times the kVA actual load. Even though that extra
.414 load is not actually doing work, it is no longer available to the
grid to do work, so it must be billed somehow, or else balanced out by a
capacitive load of equal size.

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