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Re: Here pig pig pig
Tesla List wrote:
>
> Original Poster: "Bill the arcstarter" <arcstarter-at-hotmail-dot-com>
>
> Coilers,
> Well I am in possession of my pig! No - it didn't weigh a mere 125 lbs
> as advertised. The true weight is 300 lbs + 25 for the pallet it was
> strapped to!
>
> I am now famous at work for having a pole transformer delivered to the
> loading dock! I came back with my pickup and grabbed it (lined up the
> powered loading elevator with the bed of the truck and pushed it in
> using a pallet jack).
>
> Just tonight I completed welding a cable winch onto the end of my boom
> arm - and was able to use said instrument to get the transformer off the
> truck, onto the ground. :)
>
> The transformer appears to be BRAND NEW - no rust, white paint, the
> wire lugs are tight down and don't appear to have ever clamped a cable.
> The can is roughly 16 inches in diameter and 28 inches tall. The input
> insulator is over a foot long which places the top of the insulator at
> about 41 inches off the ground! It isn't small or portable and is not
> quite what I expected.
>
> Total bill was $94 + $70 s/h. Not a bad deal. I will get the relevant
> addresses/URLs for anyone else interested in adopting such an electric
> animal. I also have yet to pursue those mini-pigs in the local scrap
> yard.
>
> There is no top access plate so I don't think it has a tap switch. I
> can take the entire top off (including the input bushing) which I will
> do to inspect the insides.
>
> There is what appears to be a pressure blow-off port at the top of the
> can. (a spring-loaded pull-ring)
>
> It contains the traditional three lugs for 120-0-120 connection, and
> the '0', or neutral lug is also bussed to the case of the transformer
> (this is removable). There is also a separate lug welded right to the
> case.
>
> I'm going to have to find some sort of wheeled platform for this thing
> to sit on. Either that or I'll put wheels on the pallet and call it
> done!!
>
> I was thinking about how to power the darn thing... I have a 240 v 28
> amp variac and various limiting devices (including a welder). But the
> problem is that if I use the variac - what becomes of the neutral
> connection on the pig? I can't connect it to the neutral bus - since if
> I did - then one 120 volt primary of the pig would always see a full 120
> volts (from N to Hot). Also - since I have only one HV output and the
> other side is connected to the case - I'd really need to keep the case
> grounded and connected to neutral. The only solution I see is to use an
> isolation transformer between the variac and the pig. This should allow
> me to tie the pig's N to system N/ground, and power the pig's 12v lugs
> off the isolation transformer.
>
> It just so happens that I have a 20 amp 240v toroidal 1:1 isolation
> transformer!
>
> Does anyone think I should break the pig's N-to-case link, tie the
> pig's case to a good RF ground, and then tie the pig's N to the power
> neutral? I think that might be the best plan.
>
> Oh - I depotted our 37 amp line filter which the tesla coil killed. It
> is hard to tell but it looks like the RF arc'd from one hot wire,
> through the potting tar, to the case. That tar just barely became soft
> at 350 degrees (in a toaster oven). I would think that the heat time to
> depot a large neon would be at least 12 hrs since this 4x3x1 inch filter
> took over 2 hrs to melt and there wasn't any iron to heat either!
>
> More later. Comments invited.
>
> -Bill
>
>
>
> ______________________________________________________
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Bill,
Congratulations on scoring what sounds to be a fine 'pig'. Remove the
external strap that ties the low voltage winding center tap to the case
and throw it away. From then on, forget this terminal exists, don't use
it. Run your 240 volts through appropriate line filters, then into your
240 volt, 27 amp variac. From the variable variac output (wiper) run
through a suitable ballast reactor then to one of the 240 volt pig
terminals. The other 240 volt pig terminal goes back to the zero output
common end of the variac. BTW, it is actually a good idea to put RF
suppression line filtering between the 240 volt pig winding and the
reactor and the rest of the control system. This can prevent RF
kickback from toasting your variac where the brushes are sitting at the
time under certain nasty condiditons. A good place to mount this line
filter is right on the pig case below the 240 volt terminals. Ground
the filter to the pig case directly. Use the pig's can connection as a
common tie point to return primary RF circuit current (one terminal of
the rotary break, one side of the tank circuit) as well as tie it to
your electrical ground in the control cabinet (control pallet?). Run a
small guage like #6 or #8 AWG from the pig case terminal out to your
coil tower along side the HV wire (I'm assuming your capacitor and break
will be located under the resonator as that's what I usually do). At
the resonator base you should have a heavy ground terminal to which a
heavy welding cable (#2 AWG or preferably heavier like #1/0 or #2/0)
should run off to your earth ground rod system. Keep this heavy ground
cable as short and straight as your setup will allow. Up to 50 feet of
#1/0 run straight without snakes and turns to an excellent ground rod
system is not a problem in a 10-15 kVA system. The bottom end of your
HV resonator ties directly to this point. A primary strike rail if
employed ties to this point. The #6-#8 AWG ground cable running back to
your pig case also ties to this common point. If you ever deliberately
run an outboard metallic strike target with a ground wire attached to
it, return that target wire to this coil base ground connection as
well. This will help minimize generating interference and inducing
stray voltages in nearby circuits.
Be careful and have fun.
Robert W. Stephens