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Re: is it useable?
Original poster: "marc metlicka by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mystuffs-at-orwell-dot-net>
Tesla list wrote:
>
> Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<davep-at-quik-dot-com>
>
> > Hi Poobear,
> > From the looks of the core size on that puppy, It could be good for 30+
> > amp even? It's hard to see the internal windings on such a beast, Are
> > you sure it isn't flat wire wound?
>
> > Anyway, I would use it as the main coiling line voltage starting point
> > in your lab, Wire dedicated terminal strips off of the output from this
> > transformer and always plug your coiling activities into these. This
> > would isolate any kickback trash from entering the line voltage to the
> > house or garage.
>
> Isolate, agreed.
> 'any' is a bit strong. Isolation transformers, except
> as below, have an amount of interwinding capacitance.
> This leads to HF/RF (EMI) coupling via this capacitance.
> The conventional isolation transformer is designed for
> 'dc' and '60 Hz'(ish) isolation.
>
> Serious Work uses special transformers, with added
> shielding isolating the load side from the line side.
> Those I have seen are specifically marked.
>
> I am NOT proposing it not be used. However
> understanding what can be expected is commonly helpful.
You're right in a small sense, If the core be grounded with a dedicated
ground and the tranny is a true ISO. tranny then most RFI will be held
within the secondary windings. EMI is a different story because this can
be induced into the wiring on the primary side very easily, shielded BX
cable with the armour flex grounded will help here. I also have worked
with some massive ISO. transformers, In fact the largest was driving
four scr bridges of twin 9000 hp dc motors. These motor control drives
would gate the drive bridges at 0 to 12khz in seconds at a step down
from 13800v to 550v and currents of 12000 amp, "much trash".
Maybe i should lay out a plan for the general coilers lab power
supply, there are many new list members since my absence so there may be
a need for help here?
The most important and first thing a coiler should do is establish a
good ground point, dedicated to all coiling power taps. I myself use two
copper clad ground rods driven six feet into the earth just outside the
window of my lab room. These rods are four feet apart and connected to
twelve feet of aluminium gutter guard witch is like an expanded metal
and can be found at home depot very cheap, I buried it four inches under
the sod along my house.
Then the next step i took was to rearrange my house distribution panel
so that the 240v\40 amp breaker dedicated to my lab was at the very top
slots. The reason for this is that if any trash does get through, it
wont effect any other lines as it travels out to the pole transformer
and ground rod.
Best case scenario is to run a dedicated circuit to the lab using
armour flex with the shield grounded to the dedicated ground grid, In
the realm of normal house wiring with romax in the walls i would suggest
opening the one outlet that is in the lab room and adding the outside
ground lead to the unused or tapping onto the ground of the outlet This
allows the path of least resistance to ground. In choosing an existing
outlet It would be optimum that this line run straight to the panel,
many contractors share loads among several rooms, I personally don't
agree with this, but that could just be the industrial in me?
I bought a nice 30 amp line filter off of ebay that i connected the 240v
BX (shielded cable) to from my dedicated circuit, This i ran to the
three 240v outlets of different configs (if you look, there are several
different stab in configs) Then i also run one leg of the 240v into a
3kva ISO transformer. This i use to wire all my test bench terminal
strips to. I plug any and all my coiling needs into these, The MOV's
within the strips are the first line defence and then the iso. tranny
and finally the filter.
I have scoped the line before all this and have yet to see any trash or
blow a breaker, RFI has a way of heating a thermal trip breaker with
only 25% current draw.
Next, I use the second ground rod as a ground terminal to connect all my
RFI grounds from my systems in operation. One more thing, I am lucky in
that my lab has rock lath\chiken wire plaster walls, If you want to
isolate the RFI to the lab itself I suggest putting the same aluminium
gutter guard from home depot on the walls and ceiling of the lab and
ground connect all to the second RFI ground rod (this stuff is
fantastic). It is 6" wide so you can leave a 6" spacing between each run
(window screen does not work).
Well, These are my suggestions, If any questions please ask.
Take care,
Marc M.
>
> > I use a huge filter but i want to upgrade to a nice iso.
>
> > transformer like this soon.
>
> I'd use both, unless the isolation transformer is
> is also shielded...
>
> > great find,
>
> Indeed...
>
> > Marc M.
>
> > Tesla list wrote:
> >
> >>Original poster: "Cajun Coiler by way of Terry Fritz
> >>
> > <twftesla-at-qwest-dot-net>" <cajuncoiler-at-cox-dot-net>
> >
> >>While cleaning out the lab, I found an old friend hiding amongst the
> >>families of dust-bunnies... a 120/240 15A isolation transformer. He
> >>was extracted from an ultrasound controller, back in `94. See it at:
> >>http://members.cox-dot-net/cajuncoiler/Images/it.jpg
>
> >>Question is: can it be used in some useful function in a Tesla Coil?
> >>Keep in mind, the 15A rating is a guesstimate, going by the internal
> >>wire size, but seems to handle 15A with no significant heat build-up.
> >>(could secretly be a 20, maybe?)
>
> >>The only clue I have, as to it's manufacturer, is what's left of a
> >>small gold logo label on top... starts with "B", ends with "on".
>
> --
> best
> dwp
>
> ...the net of a million lies...
> Vernor Vinge
> There are Many Web Sites which Say Many Things.
> -me