Re: CD 942 failure tonight

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

Original poster: Kreso Bukvic <kreso.bukvic-at-kc.htnet.hr> 

Yeah that are yours caps than can take much abuse Terry and Mark :-))

Best Regards

Kreso Bukvic
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, February 29, 2004 2:31 AM
Subject: CD 942 failure tonight


 > Original poster: "John Richardson" <jprich-at-up-dot-net>
 >
 > Hello,
 >
 > Copnsidering the recent MMC debate,  I figured that I would share this
 > evening's run.  This is a first fire, and tuning was done at partial
variac
 > setting.  Volt and amp meters are not in yet, so I can't give any real
 > numbers.  Also, SRSG was set using a flourescent bulb, as I am still
 > waiting on my motor run caps for John's phase controller.
 >
 > Here are the specs:
 >
 > Topload: 4x24  Soon to have an additional 4x36 on top of it.
 > Secondary:  4.5 OD PVC with 36" of heavy build #24, 1481 turns.  Plan on
an
 > 8" with an 8 by 36 toroid in the future.
 > Primary:  .25 Cu tubing, .25 between turns, 16 turns total, seems happiest
 > tapped at 6 and 5/8 turns.
 > Gap: SRSG
 > Safety across RSG:  Set at .5"
 > NST safety gap:  5/8"
 > Trans:12000/120 NST
 > Capacitor bank:  4 strings of 9, total of .0667, per MMC chart.
 >
 > After rough tuning and ramping up variac, I heard one cap blow.  Black
soot
 > and a hole about a quarter inch deep.  Soldered up a new one, and ramped
 > variac up to 120 volts.  Sparks about 4 feet, and gap won't fire until
 > variac is above 60%.  After that it will fire all the way down to about a
 > quarter turn on the variac.  Checked rotary, and there is no follow around
 > with the gap arc.  She fires right on electrode alignment, so I am
assuming
 > that phase is pretty close.  Started it up again, and tried to fine
 > tune.  A half turn either way from the tap point of turn 6 5/8 and
 > performance diminishes.  Put tap back at this point and fed the trans the
 > full 120 volts.  I stopped things again to check everything out.  First I
 > checked the variac, an ancient Ohmite, to see if it was getting warm.
It's
 > only rated for 10 amps, and I made a new brush out of a piece of brass due
 > to no access to new parts.  Everything looks good and runs cool.  The
lash
 > up wiring to the coil primary is 14 gauge, and it is hot to the touch, and
 > the primary is warm.  Will go to #8 for final set up.  Looked at cap bank,
 > and the new cap looked like a piece of popcorn that had just popped, black
 > and all.  The one on the next string over was bulging like you know what,
 > but no black stuff.  I can see the foil, however.
 >
 > Why is this happening?  I am not going to re-fire the system until the
last
 > portion of the tank wiring is replaced with #8, PFC caps and meters
 > installed, phase controller up and running, and new toroid installed.
I've
 > put lots of work into this thing, including welding up a nice stand for
the
 > controller, gap, trans and cap assembly, and want to get to the bottom of
 > this cap problem.  Any thoughts?
 >
 > Thanks,
 > John Richardson
 >
 >