Re: RE: [TCML] mmc cap protection by spark-gaps-any ideas?

[CONOR WHYTE <cjwhyte@xxxxxxx>]

That was what  I was trying to say.  Some MMC designs I have seen use an over volt gap over the entire MMC to protect it. -- are you saying this is a bad idea? mike hammer used this design and it proved reliable for him. personally I have never used it. The caps i use allow me lots of breathing room. CDEs are simply awsome!! 
The resistors are safety for the operator. Like I said it is a waste of energy and $$. 
You can simply discharge a gap with a discharge wand after the power is off. 
 

----- Original Message -----
From: S&JY <youngs@xxxxxxxxx>
Date: Monday, August 18, 2008 12:26 pm
Subject: RE: [TCML] mmc cap protection by spark-gaps-any ideas?
To: 'Tesla Coil Mailing List' <tesla@xxxxxxxxxx>

> No, no, no!  Don't do that!  If one or more of the 
> gaps fires, the other
> caps in series will overvolt which could cause them to 
> fail.  
> 
> The resistors are not to protect the caps.  They are to 
> protect you from an
> accidental dangerous shock by bleeding down the voltage stored 
> in each cap
> in a few seconds after you turn off power.  
> 
> You can make good high voltage resistors by series connecting 5 
> 2 meg 1/4
> watt resistors.  Connect one of these resistor strings 
> across each cap.
> Yes, lots of soldering, but the resistors are only 1 US cent 
> apiece (get
> them in lots of 100 from Jameco).
> 
> --Steve Y.
> 
> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] 
> On Behalf
> Of vatercox@xxxxxxx
> Sent: Sunday, August 17, 2008 3:23 PM
> To: tesla@xxxxxxxxxx
> Subject: [TCML] mmc cap protection by spark-gaps-any ideas?
> 
> Dear List
> I have 30 x 47nF polypropylene metal foil caps, each rated at 2 
> kVDC 
> which I intend to wire as three strings of 10 capacitors for 
> approximately 14nF at 20kV DC. While normally each capacitor in 
> an MMC 
> would be protected by a 10- or more megohm high voltage resistor 
> these 
> have proved difficult to obtain (due to lack of demand?). In liu 
> of 
> this would it be possible to protect each cap with a miniature 
> spark-gap -perhaps a pair of closely-positioned stiff wires 
> connected 
> to the capacitor leads notwithstanding the fact that 2 kV is 
> usually 
> regarded as a bit on the low side for satisfactory spark-gap operation
> 
> Jolyon Francis Vater-Cox
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