Capacitor test results
* Carbons Sent to: Esondrmn-at-aol-dot-com
Quoting Ed Sonderman <Esondrmn-at-aol-dot-com>:
RE: Capacitor test results
> Well, I finally got the test results back this morning from
> Condenser Products. I feel somewhat foolish for sending them a
> perfectly good capacitor.
A simple mistake, nothing foolish about it really. The tank
circuit pulse cap is one of the most troublesome/difficult
components of a coil system, and with a system failure like yours
this unit is naturally highly suspect. I define "foolish" as
contacting the body to live tank circuit/HVAC bussing.
> They hipot tested the unit at 35 kv with rapid charge and
> discharge. They pulse tested it at 22kv with 3 pulses per
> second and then went up to 8 pulses per second. They tested
> the internal resistance and the capacitance value - everything
> looks great.
This is that extra mile, service after the sale, that brought me
to place such a high recommendation on Condenser Products in the
first place. Scott Myers agreed, now a whole bunch of people out
here own similar units. To "recap" this: Ed purchased a 15 KVAC
.025 uF pulse cap from Condenser Products at my recommendation (I
think) long before Scott Myers "shopped till he dropped" and put
together the first group purchase (the second group purchase
should be ready to ship in a matter of days). Ed's cap is rated a
full 5 KVAC lower than the caps purchased by the group, and he
has been running this cap with 14.4KVAC inputs. It has been beat
upon a bit, but apparently still exceeds the plate specs.
To add a note of my own: I spent the better part of last weekend
beating up my .025 uF 20KVAC Condenser Products cap from the
first group purchase. I was running hard with inputs up to 25KVAC
RMS into my eight inch coil: wall to wall, floor to ceiling,
white hot bolts everywhere. After 5 minute runs with 6-8 kVA
inputs I can report that I felt some moderate warming on the
solid brass stud terminals; I feel the unit could easily handle
much longer run times without worry of failure. Still, it was
kinda nice to hear about Ed's cap.
> Now I'm really confused. There are not that many components to
> this system and it isn't really all that complicated.
HA! If there was a bunch of truth to this then there would not
be a full time internet mailing list devoted to troubleshooting
and other coiling idiosyncrasies. I am not poking fun. Coils
appear to be simple but.... no need to be verbose, we both have
some experience trying to figure these damned circuits out.
> Once again, I was running for the first time after rewiring the
> gaps, capacitor and primary interconnections with 3/8" copper
> tubing. I also move the gaps and capacitor up a bit to shorten
> the interconnect length. I had ran the system for maybe 5
> minutes trying different tap positions, running at low power -
> about 18 amps primary current and 175 volts into the pig.
> Everything was fine, the gaps were snappy and hot and I had a
> few feet of secondary discharge. I made another tap
> adjustment, turned it back on and the gaps would just barely
> fire, the primary current dropped to almost zero and the
> primary voltage went up to 240 volts. Sounds just like the
> load on the pig went away.
> I checked the gaps and the wiring and everything looked fine.
> I reconnected the system and still had the same problem. I
> mounted some copper tubing on the pig and bent it to form a
> Jacobs ladder. Then using the same primary controls,
> powerstat, line filters, welder, oven elements, etc. I tested
> the pig. Nice hot sparks which after a few minutes gets the
> copper tubes so hot they would like to fall over. The
> pig looks good.
> What else is there?
When I encounter a problem such as this I generally take the
system down the bare components: safety gap, static gap, primary,
secondary, and ground. I remove, unhook, disconnect, whatever, to
get the simplest tank circuit/resonator combination possible. No
HV chokes, bypass, HV cable, rotary, current limiting, etc..
I use 9kv neons to test medium/large systems, banked to give
sufficient amperage to give a decent match to the tank capacitor.
I "hot" test the neons by pulling an arc or using a Jacob's
Ladder to make sure the phasing and performance of the power
supply are up to snuff, then throw the juice directly to the coil
using simple hookup wire run on insulators. It is assumed the
system is at least roughly in tune, and a well known static gap
is in the tank circuit. It really can't get much simpler than
Once the system is fiddled with and working smoothly and
reliably, start testing and adding additional components to the
system one at a time (even something so basic as the HV lead
wires can fail sometimes and pass without notice). Static test
each component with HVAC directly from the power supply before
connecting the component to the coil system. Then test fire the
entire system after each component is added. Once all tank
circuit/HV feed components are on line and the system is
functioning, then swap in the higher voltage pole pig (or other
power supply) with the required current limiting. No two systems
are really identical, it would be up to the builder to determine
the order that specific components should be added to the system.
Operating the system at lower voltages at the start of a trouble
shooting session reduces the input power (allowing the operator
to get in closer to examine the circuit under a load) and makes
flashover, arcing, and burning less of a problem. Being closer
may allow you to see or hear a short, poor connection,
burning/arcing wire, etc., better than being backed off as is the
case when working with higher voltages (and higher peak powers).
One way or another, this simple trouble shooting proceedure
should uncover the problem. The problem area will typically show
up when a component fails a static smoke test or after it is
swapped into the running and tuned circuit. Either way I would be
surprised if an evening of troubleshooting in this manner would
not uncover the problem.
... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12