Re: series pigs

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

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

I assume that Greg (the first) is running low voltage in parallel and high
voltage in series, so he would be getting 20 kVA at 22kV.. or, if HV
windings in parallel, 20 kVA at 11 kV.

Probably a more important issue is going to be the capacitors.  You're going
to have the same basic stored energy (since that's the 20 kVA in...) in the
capacitors total.  If you're using MMCs, the max energy that can be stored
in one little cap is the same regardless of configuration (set by C and max
V), so at a first order, the cap cost is the same.  However, there are max
RMS current limits, and certain arrangements of caps work better (i.e. fewer
caps to get the required voltage and or current rating).

The spark gap losses are probably represented best by a fixed voltage drop,
so increasing the tank voltage is good (reduces the fraction of the voltage
in the gap).

Resistive losses are less at lower currents (by the square!) so higher
voltage is favored from that standpoint as well.

A tricky one to evaluate is the ESR of the capacitor(s).  Is it truly a
series resistance (at least as far as modeling)?  Consider two cases:
 you have two caps of capacitance 1 and voltage rating 1.  You can either
run the tank at voltage=1 and current=2 or voltage=2 and current=1.  In the
first case, you put the caps in parallel, so the ESR of the whole lot is
1/2.  The current is 2, so the losses are 0.5 * (2^2) = 2.  In the second
case, the caps are in series, so the ESR of the whole lot is 2. The current
is now 1, so the loss is 2 * (1^2) = 2 again.  I suspect that it works out
the same regardless of configuration.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, January 16, 2002 10:20 AM
Subject: RE: series pigs


> Original poster: "Loudner, Godfrey by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <gloudner-at-SINTE.EDU>
>
> Hi Greg
>
> In series it would be 22kV at 10kVA.
>
> In parallel it would be 11kV at 20kVA.
>
> Godfrey Loudner
>
> > -----Original Message-----
> > From: Tesla list [SMTP:tesla-at-pupman-dot-com]
> > Sent: Wednesday, January 16, 2002 8:57 AM
> > To: tesla-at-pupman-dot-com
> > Subject: series pigs
> >
> > Original poster: "Mr Gregory Peters by way of Terry Fritz
> > <twftesla-at-qwest-dot-net>" <s371034-at-student.uq.edu.au>
> >
> > Hello all,
> >
> > I would like to ask if placing pole pigs in series is a bad idea. Has
> > anyone tried this and had any problems? I would like to place two 10kVA
> > 11kV pigs in series for a grand total of 22kV at 20kVA.
> >
> > Cheers,
> >
> > Greg Peters
> > Department of Earth Sciences,
> > University of Queensland, Australia
> > Phone: 0402 841 677
> > http://www.geocities-dot-com/gregjpeters
> >
> >
> >
> >
>
>
>