Re: GE 42L series caps Good or Bad??

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

Original poster: "Steven Ward by way of Terry Fritz <twftesla-at-qwest-dot-net>" <srward16-at-hotmail-dot-com>

Hi,

I would say BAD IDEA for the .22uf at 1200v.  But for some reason, my large 
.68uf caps, are still running strong!!  I ran the large coil tonight with 
15/120 PSU and only 1 string of 24, and it ran great. I probably only have 
about 5 minutes of time on the caps, but thats better than the .33uf that 
started boiling in about 45 seconds!  I will try putting some new caps in 
their place, and see what happens.  IF they fail again, i will use the caps 
for my GMHEIC record thing that Terry set.  Im sure they will last the small 
1200v pulse every few seconds.  Im planning on twins, and a limited 15" 
spark :)  Let the coils live for awhile.

Terry, here is my question.  If there is no sign of heating, will these caps 
likely last?  I ran in intervals of about 10 seconds, on and off for about 
an hour.  I felt the body, and ends of every cap.  They were all cold!!  Im 
still getting 5 footers to the ground.  I will be trying out my new sucker 
gap (like gary lau's).  The epoxy was drying tonight, so i still had my RQ 
gap.

I think i will invest in a few more of the .68uf 1200v GE caps, but im 
staying away from anything else on the 42l's.  Why get more???  Well, im now 
1 short (i took one apart), and if one blows i will be able to replace it.I 
actually have enough caps for 2 strings of 24, but that is way too big i 
guess.  I can even have 2 cap banks on hand so that if i blow a cap, i can 
easily sub in another bank.  So ill probably get another 5 or 10.  Please 
dont follow in my foot steps!  Stick with the panasonic or CD caps.  Im not 
sure why the 3000v caps i had lasted soo long (42l's).  Maybe they used the 
foil with the metalized film.  So im still confident in my large caps at the 
moment, they are taking a beating, and dont mind it.

Terry, could it be that these caps are better because of all of that extra 
surface at the end caps? The .68uf are much larger than the .33 that i sent 
you.  But still im running 2X + the amount of power through them.  Well, ill 
try to get a lot more run time in on it to test the reliability of the caps 
(at least short term).  So is it possible that, if there is no heat build 
up, that maybe the caps will last??  Im guessing no heat= no damage.  Or are 
these caps destined to pop?

Steve Ward.


>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: GE 42L series caps Good or Bad??
>Date: Fri, 13 Sep 2002 20:33:13 -0600
>
>Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
>
>Hi All,
>
>Apparently GE 42L series are mataized caps instead of solid metal foil
>types.  Steve has some of these that burnt out at the end plates:
>
>GE  42L2332
>0.33 uF 5%
>1200 VDC
>500 VAC
>
>He took a look and some larger ones and they seemed to be metalized too!
>
>Should this series of caps be teken off the good caps list?  I always
>thought they were foil :-(  Steve ran his really hard with just one string
>(  MMCcalc say they should have worked fine...
>
>MMC Calculator  Ver. 2.2   9/12/2000  Terry Fritz
>Transformer voltage =  12000
>Transformer current =  .06
>Firing voltage =  16970.52
>Fo =  150000
>Break rate =  200
>Thermal dissipation constant =  33
>Individual cap value =  3.3E-07
>
>Strings  Caps/Str  Capacitance  Voltage   Temp C    Cost              I 
>Arms
>   1       20         16.50        24000     1.72   20.00  :-))  :-))  3.44
>--------------------------------------------------------------------
>
>
>Cheers,
>
>	Terry
>
> >I just finished up a medium coil powered by a 12/60 and a static gap.  My
> >MMC is 20 in series of 1200v .33uf caps for .0165uf -at- 24kv.  Well the 
>coils
> >performance was poor to say the least with only 2 foot arcs.  So i tried 
>and
> >tried with no luck.  So just out of curiosity, i felt the caps after i
> >turned it off.  They were hot!  well 2 of them were.  I let them cool 
>off,
> >then ran it again.  Checked for heating, it was still in those 2 caps.  
>One
> >was hotter than the other.  So i took them out.  I took apart the really
> >warm one and found some depressing realizations.  The ends of the foil 
>were
> >totally burnt to a crisp at one end!




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