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Re: PFC Question
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- Subject: Re: PFC Question
- From: "Tesla list" <tesla@xxxxxxxxxx>
- Date: Sat, 12 Nov 2005 18:03:38 -0700
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Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>
They will saturate. That's why when we used to use old variac cores
we always gapped then at .080 inch. A fabricated steel clamp held
the variac from spring apart and a bandsaw did the work. An 80 mil
piece of plastic was epoxied in place to form the gap. They didn't saturate.
Now we use our own slug tuned cores with a small DC gearmotor to
accomplish the same control and makes it a completely variable
process. Current is adjusted completely independent of voltage.
> Original poster: Ed Phillips <evp@xxxxxxxxxxx>
> I have never understood why saturation isn't a factor in using an
> ungapped variac in series with a load.
Ed, i think we speak about the case of using the variac as an
autotransformer, not as variable inductor.
> An easy check on the leakage impedance would
> be to short the two ends of the winding and run say about 1 amp (100
> watt bulb in series across 120V line) and measure the voltage drop
> between the brush and the shorted ends for different brush
> positions. Why don't you do that and publish the results here? Only
> a few minutes work.
imo it will be difficult to get an acceptable accuracy of the
measurements, as the resistance of the winding can be compared
with the leakage inductance impedance, and it`s worse - both these
values are very small. for example, i have only usual dmm - i haven`t
got a measuring bridge.
we have to make the measurement by comparing the voltages (as i
suggested before in the thread about my psu), but i need one more
variac for this.
The solution to no primary hits lay in getting rid of the primary!
This is no joke either.
20-06-96 (c) Richard Hull, TCBOR