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Re: Repost: NST VA Rating and Power Factor

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

> Original poster: "Pete Komen by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> Original poster: "Jason Petrou by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <jasonp-at-btinternet-dot-com>
> >  My power supply consists of three 15/60 NST's.  Two are Franceformers,
> >  and are marked 495 VA, and also have "High Power Factor" on the label.
> >  The other is a Magnatek/Jefferson, marked 900 VA.
> If you do the math (15000V*0.06A) you get 900VA - which is what it should
> for all 15/60 NSTs. I have no idea how you have got just under half that
> the franceformer ones... it is technically impossible :)
> incorrectly. I dont know what the High Power Factor means - i'd check with
> the company (or wait for other replies from the list
> I have two NSTs, both 12kv at 60ma, high power factor (rated 400va).  It
> my understanding that the HPF NSTs have a built in capacitor to correct
> current lag due to the inductive load.  Adding the PFC cap reduces the
> current without reducing the output.

Which reduces the VA without reducing the Watts.

 See also Terry's posts on PFC caps.
> Adding PFC caps to a HPF NST doesn't make sense.  Maybe someone else can
> give you the technical details.  Maybe I'll check the input current on

It "might" make sense, if the power factor in TC use is different than in
"luminous tube" use, which, off hand, seems likely.  A bit of
experimentation would answer the question. I suspect that no amount of
theoretical figuring would an answer that could be trusted, because the
power flow in a TC is somewhat strange, and certainly not linear.