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Re: Inductive Kick LTR Pig Systems
Hi Marc, Terry,
Tesla list wrote:
>
> Original poster: "Metlicka Marc" <mystuffs-at-orwell-dot-net>
>
> Tesla list wrote:
>
> > Original poster: Terry Fritz <twftesla-at-uswest-dot-net>
> >
> > Hi Marc,
> >
> > The RMS current through those caps should be the same as any PFC
> > application. My first thought is the 680uF is a pretty large continuous AC
>
> > cap value and perhaps it is a motor start or intermittent duty cap.
>
> yes they were motor start caps, it never occurred to me that i was using them
>
> in the wrong application? (hind sight again)
>
> > I
> > think you save these two caps in series for 340uF but that should not
> > explain the heating. It is also possible that there is some resonance
> > going on between these large caps and the pt somehow.
> >
> > In the configuration that the two 680uFs were overheating, Could you tell
> > us what the connections were (I assume in series across the AC line right
> > before the PT. Also if you could mention the PTs specs too.
>
> the caps were paralleled across the line after the main contactor, before the
>
> pt. the new caps are mallory 40-48uf, 220ac. these exhibited some warming but
>
> that was after one old one that i used in other experiments blew, i think i
> hurt it? i am getting some more caps to build a new matched bank. the Pfc.
> for
> the 2kva stepper trans. are the new Mallory's and they seemed to warm also
> but
> not much and maybe my imagination?
> the pt is a 110/33000, 300-1 unit. single terminal. i am running 120v into
> the
> stepper and 70v out to the pt.
> there are things on the pt label that make no sense to me but if you or
> anyone
> would like to decipher it i'll post.
> marc
Wouldn't this particular transformer use something like 4000uF for full PF
correction? This is what my calc's are telling me anyway (assuming 110V,33KV,
454mA, 15KVA).
PF Cap(uF) = (KVA * 10^9) / (2 * pi * F * Vin^2)
Bart