Re: PFC, Do you advocate them on 14440 1 amp transformers? (fwd)

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---------- Forwarded message ----------
Date: Tue, 24 Oct 2006 00:41:10 -0600
From: Gerry  Reynolds <gerryreynolds@xxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: PFC, Do you advocate them on 14440 1 amp transformers? 

Hi Jim,

Its easy to think of it as backwards until one realizes the reactance of the 
capacitor goes down as the capacitance goes up (XC = 1/(2*pi*freq*C).  When 
you restate the reactance of Cp for the primary, the reactance needs to be 
divided by n^2 (n=turns ratio).  If LTR, the capactive reactance (restated 
for the primary) will be smaller than the ballast inductive reactance. 
Since net reactance will be XL - XC (series circuit), the inductive 
reactance XL wins.


Note what happens to the current limiting ability of the ballast as the LTR 
Cp is reduced and approaches resonance.  This will have a great affect on 
the current if using a 120 BPS SRSG.  However, the current will not scream 
high if using a properly set static spark gap where the output voltage is 
limited by the SG since AC steady state can not occur for this case.  I 
would need to simulate it to see what happens for a high BPS RSG when 
running at resonance.

Gerry R.


> Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>
>
> Thanks Gerry,
>
> That's the first time I've heard the STR Scenario which is what I will be
> running; but, are you sure you didn't state that backwards?
>
> Jim
>
> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx]
> Sent: Saturday, October 21, 2006 9:11 PM
> To: tesla@xxxxxxxxxx
> Subject: Re: PFC, Do you advocate them on 14440 1 amp transformers?
>
> Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
>
> Hi Jim,
>
> Your PFC should be across the power line (or variac output) with the
> inductive ballast in series with the PIG LV input both located
> downstream from the PFC.   Since the PFC has a "zero" impedance
> voltage source across it (the line or variac output), its current
> draw will only be seen by the source and will not affect things
> downstream.  Since the run caps are rated for the line voltage you
> are using, there is no need to worry about current rating for these
> applications.
>
> Capacitive PFC will only help if you are using a LTR value of Cp as
> the reactance of the LTR value cap reflected to the primary will be
> smaller than the reactance of the ballast inductance in series with
> it, and hence the load presented to the line will still look
> inductive.  If STR opearation is contemplated, the load to the line
> will look capacitive and an inductive PFC will then be needed to
> cancel this out if desired
>
> Gerry R..
>
> >Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>
> >
> >Hi again,
> >
> >I am considering buying 1000uf @ 370v Run Caps (100uf ganged) for PFC. I
> not
> >to worried about the current, I'll be using a Nema 5 contactor.
> >
> >Will this effect the performance of the coil. I seem to remember reading
> >somewhere that they add a kick as well as increase efficiency. Does the
> >power company see a difference? I also seem to remember that they don't 
> >see
> >inductive loads well.
> >
> >My source for the transformer is Jack. We all hear from him from time to
> >time . He has lots of HV toys. I will be using a 15kva sliding choke
> >actuated by a surplus satellite actuator. Hey, I like the idea of a 
> >rocker
> >switch to control current! I've already leaned my lesson about putting 
> >movs
> >across switches and maybe to ground too.
> >
> >Jack if you are reading this , please respond with a comment about using 
> >a
> >PFC bank associated with a slide choke, on the bombardier Transformer. 
> >The
> >effect of the capacitance and the varying inductance is interesting.
> >
> >Comments?
> >
> >
>
>
>