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The Pig Uncovered




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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