Re: CD 942 failure tonight

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

Original poster: "John Richardson" <jprich-at-up-dot-net> 

Hi Gerry,

Thanks for the advice.  Most certainly am seeeing excessive current loading
with the small wire.  I was getting longer sparks with a 12/60 and a simple
Cu pipe gap.  Need to fine tune things a bit.

Thanks,
John
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, February 28, 2004 11:39 PM
Subject: Re: CD 942 failure tonight


 > Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net>
 >
 > Hi John,
 >
 > Possible causes for blown MMC that I can think of:
 >
 > 1.  Cres for a 12K 120ma tranny is 26.5 nf.  With SRSG you will need ~3.1
 > times Cres (or 83 nf) to keep voltage rise (inductive kick) from exceeding
 > rating.  You are using 67 nf which could allow excessive rise.
 >
 > 2.  Irms spec for C is exceeded.  Probably not since you have 4 strings of
 > .15uf cap.  What is you pps  120 or 240 or more?  Since your lash up
wiring
 > and primary are getting hot, your RMS current must be very high.
 >
 >
 > 3.  Inadequate clearance between CDE cap body and other components (such
as
 > bleed resister).
 >
 > 4.  With too small of a toroid, the number of turns on the primary may be
 > too low causing peak current to be too high.  6 5/8 turns seems somewhat
low
 >
 > Run JAVATC and it will tell you what peak current and energy transfer time
 > are.  This will help put somethings into perspective.
 >
 > Gerry R