# [TCML] Bleeding resistors for MMC

Lau, Gary Gary.Lau at hp.com
Sat Feb 27 18:51:39 MST 2010

```No.  The situation can be summarized briefly and accurately as:

When using 0.1 or 0.15UF/2000V caps in an MMC, wire one 10Meg/0.5W resistor in parallel with each cap.  Doesn't matter how many caps are in the string or how many strings you use.  If the cap is properly designed, this will work and is what you need to do.

Assuming the cap array is properly designed so that each cap's peak 2000V rating isn't exceeded, each resistor will dissipate something less than 0.2W.  Assuming the PEAK voltage across the cap is not more than 2000V, the maximum RMS voltage is 1414V.  1414x1414,10,000,000=0.2W.

Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces at pupman.com [mailto:tesla-bounces at pupman.com] On
> Behalf Of Brandon Hendershot
> Sent: Saturday, February 27, 2010 6:59 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] Bleeding resistors for MMC
>
> OK,
> with that said, how do these values sound?
> P=0.00033333 watts
> t=0.15 seconds
> I don't know what to look for exactly, do I need more ohms? Less
> watts? It's a 10M ohm 1/2 Watt resistor. 2Kv 0.15uf caps.
>
> I can't say it enough, THANKS EVERYBODY!
> Brandon
>
> On Feb 27, 2010, at 3:46 PM, jimlux <jimlux at earthlink.net> wrote:
>
> > Brandon Hendershot wrote:
> >> Great! Thanks a lot Jim, Henry, Joh, that really cleared it up.
> >> Now, last thing I'm going to have to bug you guys with. In the
> >> formula "P=V^2/R", when you say "V is the voltage across the
> >> capacitor (volts.)", do you mean the voltage from the power supply
> >> divided by the number of capacitors, or the rated voltage of each
> >> capacitor?
> >
> > The voltage on each capacitor.. that is, power supply voltage
> > divided by # of caps.  And it's RMS voltage, not peak.
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```