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The Pig Uncovered
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From: D.C. Cox [SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent: Monday, February 16, 1998 1:59 AM
To: Tesla List
Subject: Re: The Pig Uncovered
to: Greg
You are right -- the core/coil assembly weighs approx 100 lbs. It's in all
that oil for two reasons --- thermal considerations such as operation day
after day at 110 degrees summer temps and dielectric testing required by
125 kV BIL (basic impulse level) which requires a considerable separtion of
the assembly from the tank walls. This in turn requires a lot of space and
a lot of oil at 7 lbs/gal. We remove the rascals completely from their old
tanks and use a simple 13 x 13 x 14 inch high 10 gauge steel case welded
up. For the top lid to run the 220 volts in and the HV out we use a 1/4
inch thick piece of type LE phenolic plate. The lid has a 5/8 inch flat
lip all around and machine screws every 2 inches. Add some small gasket
material to this lip all around. One end of the HV is grounded to the case
and also a separate ground connection is brought out with the 220 volt
primary thru 5/16 in brass bolts. HV comes out through a small 1/2 in dia
polystyrene tube which protrudes down into the oil and sticks up off the
lid approx 4 inches -- provides venting and prevents oil from splashing
out. Entire assembly with 10 kva core/coil is 120 lbs total weight. Even
a 5 gal. plastic bucket beats lugging around a 300 lb pig or smashing your
fingers/feet. Fill with xmfr or mineral oil and Tesla away!!
DR.RESONANCE-at-next-wave-dot-net
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> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-pupman-dot-com>
> Subject: The Pig Uncovered
> Date: Sunday, February 15, 1998 7:02 PM
>
>
> ----------
> From: Gregory R. Hunter [SMTP:ghunter-at-mail.enterprise-dot-net]
> Sent: Sunday, February 15, 1998 2:25 PM
> To: Tesla List
> Subject: The Pig Uncovered
>
> List,
>
> I took the lid off of my pole transformer, just out of curiosity. In
> the UK, pole pigs are upright rectangular boxes, with the HV
> insulators on the top-front and angled up & out at about 45 degrees.
> My 5KVA, 11KV unit is so heavy, I use a 600 lb dolly to move it
> around, and it's still a struggle. The thing must weigh 300 lbs.
> That's one thing I was curious about--why does a 5 kilowatt
> transformer weigh so much? I've got some notion as to the the
> required cross sectional area for a 5KVA transformer core, and this
> thing is just too heavy for its rating. And the SIZE of it--it's
> 20"H x 18"W x 11"D. Nutty. I've got 2 and 3 KVA autotransformers
> around here no bigger than shoeboxes (powering all my Yank
> appliances). So I unbolted the lid and took a peek. As I
> suspected, lotsa empty space in there. The transformer itself
> occupies less than half of the box. It's under a bath of
> crystal-clear oil. Why such a big box for such a small transformer?
> I think more than half the weight of the thing is box & oil. I bet
> the transformer itself is no more than 100 lbs. The core has a big
> hook eye welded on top. I'm real tempted to hook a chain hoist on
> that dude and repot it. If I mounted it in a smaller, lighter
> container I could probably carry it around by myself.
>
> Greg
>
> East Anglia, UK
>