Re: Capacity Value Transformation

To: tesla-at-pupman-dot-com
Subject: Re: Capacity Value Transformation
From: "Ed Phillips" <evp-at-pacbell-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Sat, 22 Apr 2000 16:13:20 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Tesla List wrote:
> 
> Original Poster: "J. B. Weazle McCreath" <weazle-at-hurontel.on.ca>
> 
> Hello Coilers:
> 
> While reading a text on A.C. motors I came across an interesting circuit
> that might have application in Tesla coil power supplies.  The value of
> a capacitor can be increased by the use of a transformer, as in this
> example.  A transformer with a primary/secondary voltage ratio of 1:2
> has a 20 uF. capacitor connected across its secondary.  This causes an
> apparent capacity equal to the ratio squared times the capacitor value,
> in this case 80 uF., to be across the primary.
> 
> I'm wondering if by using a relatively low KVA rated 1:2 ratio transformer
> one could achieve power factor correction with relatively small values of
> PFC capacitors.  This would be particularly useful for larger coils that
> require capacitors in the hundreds of micro-farads for PFC.  The primary
> of the "capacitor transformer" would simply be paralleled with the MOT or
> pole pig primary.  One cap of 40 uF., a readily obtainable value in oil
> filled motor run caps, would yield an apparent capacity of 160 uF. in the
> power transformer primary circuit.


	Absolutely! Some NST's do exactly that.  The PFC capacitor is connected
to a separate winding on the same core with a turns ration of two or
more.

Ed