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NEON- Re: Dimming HPF transformers
Hello Jeff, Ted, et al
Jeff wrote...
>2. I've also heard for the first time that you can't dim High Power Factor
>Transformers. Is this true?
Yes.
> Why is this, if so?
Ted had it right. For ferromagnetic designs, we trafo manufacturers use a
capacitor loaded on the primary side of the design. This takes the normal
incoming power supply with and "power corrects it". It acts to change the
phase of the sinewave so that there are no line losses.
Now, to dimmers.... a proper neon dimmer does not work like a household
incandescent dimmer (Jeff and Ted, you probably know this...it's for the
newbies). We do not want to dial down the input voltage like those devices
do. A proper neon dimmer adjusts the phase of the waveform.
So, we've set up a conflict. The capacitor in the HPF trafo is fighting to
correct the waveform while the dimming device is trying to dephase it.
Voila. Both burn up.
Things can be a lot different for solid state designs. We can build dimming
into the circuitry. So, it is possible to have electronic HPF units that dim.
Hope that helps,
Eric