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Re: Current limiting?

In a message dated 96-01-15 15:46:32 EST, tesla-at-grendel.objinc-dot-com writes:

>Hi there all,
>
>I have a number of smallish transformers which don't come with any current
>limiting on them. Now I hear of all sorts of methods of doing this (oven 
>elements, welders, variable inductances). Most of my transformers (don't
>laugh)
>push about 200W according to their spec. How is it best to current limit
>these?
>And does the process of limiting the current cause a reduction in the peak
>voltage seen by the capacitor in the tank circuit?
>
>Cheers
>Phil Mason
>
>

Phil,

You need to limit the current into the primary of a transformer being used to
drive a Tesla coil because the spark gap acts as a short circuit.  The
transformer will want to draw lots more current than it is rated at and blow
fuses and generally be uncontrollable.  You can use resistive loads in series
with the primary to the transformer to limit the current but the voltage
dropped across the load will limit the voltage into the transformer and
reduce the output voltage.  An inductive load (ballast) is used to limit the
current without limiting the voltage - uising inductive reactance not
resistance.  This controlls the current into and out of the transformer
without reducing the voltage - there actually will be a small voltage drop
across the ballast due to the resistance of the wire.

Ed Sonderman