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RE: phase shifter instead of variac use

Original poster: "Steve Conner" <steve.conner@xxxxxxxxxxx>

 > >is it possible to use a big phase shifter with current regulator for
 > >teslacoils.

Well I don't see why not. (I assume you mean a phase angle controller like a
huge lamp dimmer) I have used a thyristor phase angle controller on my
OLTC2, it allows me to regulate the DC bus voltage between 10 and 600V. I
also know of people who have used heavy duty lamp dimmers (rated for
inductive loads) to control the power of NST coils. I think it might be
possible to control my MOT-powered DC coil with a dimmer too.

However, I don't think your plan with the pole pig would work unless you
added an inductive ballast in series with the thyristor unit. Once the
thyristor has fired it is just "ON" and has no more control over current, so
there would be very high peak currents and risk of power arcing at the gap.
In your example with the locomotive welding set, the generator and
transformer probably have enough leakage reactance to keep things under
control, but pole pigs have very low reactance.

In other words, the phase angle controller is a variac replacement, not a
ballast replacement (IMO) This is why it should work fine with DC coils,
SSTCs and OLTCs (which don't require ballasting) and NST powered coils
(which are internally ballasted)

See my thyristor firing circuit here
This circuit has proved very reliable and I'm planning to use it for other
*TCs in future.

Steve C.