Re: Power factor correction capacitors for MOTs

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net> 

Hi Ed,

I too have wondered that.  There is an intrinsic inductance in the
transformer and the load capacitance should be reflected to the primary.  If
LTR operation is done, I would think the input of the transformer would look
capacitive.  Terry F. says that it still looks inductive because of the
shunts (context is NSTs).  I dont think I understand this.

Gerry R.


 > Original poster: "Ed Phillips" <evp-at-pacbell-dot-net>
 >
 > I have a question which I've posed before, without what I considered as
 > a satisfactory answer.  Since the secondary of the HV transformer
 > already has a capacitor across it, perhaps of greater than resonant
 > value, what function does the PFC capacitor on the primary perform?
 > What's it correcting for?  More importantly, how can you really select a
 > value without taking the secondary load into account?  I can see where a
 > big capacitor across the line will reduce the glitches in line current
 > caused by the firing of the gap, but other than that the usefulness is
 > not obvious.
 >
 > A few years back I experimented with PFC capacitors and a small coil I
 > have here.  I could reduce the no load current of the NST alone (no
 > secondary connection) from a couple of amps down to near zero, but
 > capacitors didn't have much affect on line current when the coil circuit
 > was connected and firing.  Under the conditions I was running the line
 > current was about 6 amps with or without a capacitor.  I could increase
 > the current above this by using a very large capacitor but why do that?
 > I should have taken notes but........
 >
 > Ed
 >
 >