Subject: POLE TRANSFORMERS
From: richard.quick-at-slug-dot-org (Richard Quick)
Date: Tue, 21 Mar 1995 00:50:00 GMT
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* Original msg to: Esondrmn-at-aol-dot-com
Quoting Ed Sonderman:
ES> As I begin to look for better transformers, can you describe your
ES> pole transformer to me.
10 kVA "pole pig" (power distribution transformer), two high voltage
bushings, primary 22890 volts, secondary 120/240, no taps. Of course
I run mine backwards so the "secondary" is my primary, and so on.
ES> How would an electric utility know what type I was talking about?
Most utilities start to get nervous about this, and would want $$$$
for a new unit anyway. Used units are EPA restricted due to PCBs, so
your best bet is to locate a supplier of "new" surplus or "rebuilt"
(PCB free) units. If you contact you local power utility ask about
"potential" transformers instead of distribution transformers.
Potential transformers are rated from 1-5 kVA in varying voltages
and are quite suitable for medium power Tesla coils.
ES> I notice most of the pole transformers that I see have only one
ES> high voltage input terminal. They must use one high voltage
ES> lead and a ground for an input.
One bushing transformers are common. The case of the transformer is
grounded with one side of the HV winding. The low voltage windings
are isolated. It is not a big deal to pop open the lid and isolate
both ends of the HV winding, but you are better off finding a trans-
former with two high-voltage bushings.
ES> I notice yours has two high voltage input leads. This would allow
ES> us to isolate the input which is what I would want. What is the
ES> current and voltage rating of your transformer? I would like to
ES> get one like that only about one half that physical size.
The "pig" in the video will put out about 20kv -at- .5 amp without warming
up. It will exceed the plate rating by a factor of three for 3 minutes,
or by a factor of two for 5 minutes before it starts to warm.
... If all else fails... Throw another megavolt across it!
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