RE: Capacitor series and balancing resistors

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>

But when used in MMC's, the 10 Meg resistors that are often placed in
parallel with each cap are not there for balancing, but rather to bleed off
any remaining charge after the coil is turned off.  

The AC impedance of a .047uF cap at 60 Hz is 1/2pi*F*C, or 56.4K.  If one
wished to use resistors to ensure that the charging voltage is equally
divided across caps in a string, such balancing resistors would have to be
much, much lower in value than the 56K.  But even a 56K resistor in
parallel with each cap, assuming it sees a peak sinusoid voltage of 1600V,
would dissipate 22.7 Watts per cap.  Clearly this is too much.

The resistors that we use should be called bleeder resistors, not balancing
resistors.

Gary Lau
MA, USA

 -----Original Message-----
From: 	Tesla list [mailto:tesla-at-pupman-dot-com] 
Sent:	Thursday, February 21, 2002 1:16 PM
To:	tesla-at-pupman-dot-com
Subject:	Capacitor series and balancing resistors

Original poster: "Marco Denicolai by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <marco.denicolai-at-tellabs-dot-com>

Hello all,

If you have been building electrolytic capacitor series, wondering about
the value of balancing resistors, here is a link for you:

http://www.bhc.co.uk/application.htm#parallel

Not the the math would be really tricky, but at least it is readily done
there. And I think it can be easily extended to series of poly caps too.

Regards