Hi all,
I was just wanting to pass on to the rest of the TCML big SG coilers the
amazing suitability that I have found of some certain GE Dielektrol
protective capacitors to be for coiling. These have been showing up on
eBay
fairly frequently as of late and are rated at 0.25 uFd @ 13,800 V(AC).
https://www.ebay.com/itm/GE-Capacitor-with-Dielektrol-9L18DCL101-13-8KV/
171955634804?_trkparms=aid%3D777001%26algo%3DDISCO.FEED%
26ao%3D1%26asc%3D50963%26meid%3Dfcbee251c09a4671967201c022e0
0f6c%26pid%3D100651%26rk%3D1%26rkt%3D1%26%26itm%3D171955634804&_trksid=
p2481888.c100651.m4497&_trkparms=pageci%3A4e91f1f4-
56ef-11e8-bfd1-74dbd1800d55%7Cparentrq%3A5b4518781630a9c10cbe75cafff4
bdba%7Ciid%3A1
https://www.ebay.com/itm/GE-General-Electric-Capacitor-
with-Dielektrol-Fluid-18L0009WH-13-800V/273049284524?_trkparms=aid%
3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D50963%26meid%
3D90ee9bc9263f44fe9a830e47dd8b0680%26pid%3D100675%26rk%3D1%
26rkt%3D15%26sd%3D382430499481%26itm%3D273049284524&_trksid=
p2481888.c100675.m4236&_trkparms=pageci%3A4e91f1f4-
56ef-11e8-bfd1-74dbd1800d55%7Cparentrq%3A5b4518781630a9c10cbe75cafff4
bdba%7Ciid%3A1
This appears to be the best current 'deals' on these units at this time.
The original units (now discontinued from production) were PN -
9L18DCL101
and the updated ones are PN - 18L0009WH. Due to a GREAT eBay "deal" on
three of these last year, I decided to try a pair of these (the original
9L18DCL101 units) in series (for 0.125 uFd @ 27,600 VAC - but measured C
is
just over 0.13 uFd) as the main primary circuit capacitor for my ARSG
driven, big pole pig coil. Once the primary coil was properly retuned for
the larger C than my original measured 0.113 uFd Maxwell pulse cap unit,
these worked quite beautifully in my coil! There appears to be no
discernable heating above ambient temperature of thier guts, although the
outer casing that is in closest proximity to the primary coil will get a
bit warm after an extended run, obviously due to magnetic heating of the
ferromagnetic outer casing, not losses of the internal dielectric system.
I
say this due to the fact that the discernab
le warmth of the outer casing completely disappears within a couple of
minutes following shutdown. From previous experience, I have found that
internal dielectric heating due to excessive dissipational losses that is
felt on the outer casing of the capacitor unit takes a considerable
amount
of time to fade after shutdown. Depending upon the internal thermal mass
of
the capcitor, this cool down can literally take hours! Even though they
are
'used', I figure that I am actually running them at a pretty 'low stress'
level, pushing only an absolute maximum of 16.8 kVAC RMS (about 60% of
their combined 100% duty cycle nameplate rating and usually notably less
than this).
It appears that these caps were designed to be used in combination with a
distribution surge arrestor to protect the windings of LARGE motors (that
run on a nominal input line voltage up to 13,800 volts!) from sharp line
voltage peaks. From what I have been able to determine online, they are
constructed with a PP based "Hazy Film" dielectric system and extended
end
foil connections and like most of their medium voltage PFC cousins, they
have internal discharge resistors to safely bleed off any residual HV
charge from the capacitor to the 'safe to handle' range within <10
minutes
after the circuit is de-energized. This is a nice feauture in my opinion,
as it 'defangs the snake' of hidden residual charge that can creep back
up
to 'bite you' even after the terminals are shorted out with a hot-stick,
due to dielectric memory, yet their resistance level is still high enough
that their extra load across the cap's terminal is totally
inconsequential
to the coil's performance within
the milliseconds time frame of the charge/discharge cycling in a Tesla
coil primary circuit.
All in all, these units appear to be constructed quite robustly, too,
both
from a mechanical as well as an electrical standpoint. So, if you happen
to
have spotted these particular caps and are apprehensive about taking the
leap, I can personally attest from a coiling standpoint that "the water
is
fine". ;^)
David
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