As you are about to venture into the area of high voltage equipment, if you
don't have previous experience in this area, you should be prepared and
equipped with the proper supplies and equipment.
It would be a good time to contemplate your earlier concern related to those
high voltage capacitors you had at one time.
You should be prepared by going to an electrical supply (not a consumer
store hardware department) for properly rated wire and all termination
parts.. this includes properly rated switches and fuses too.
A transformer like the one referred to won't shut itself off just because
there happens to be a piece of meat between/across the terminals.
Ordinary household wire isn't suitable or safe for use at higher voltages.
Jackets on romex-type jackets are marked with a 600V rating, but that only
applies as the design/manufacturing specifications rating when the wire is
used properly up into the 200+VAC range (not bent, twisted in a knot,
tightly kinked or otherwise abused).
A nick in the insulation of a conductor carrying 400+VAC is very likely to
cause an arc-over if it gets near another conductor or grounded metal part.
This hazardous event might not be so spectacular, but someone may react by
flinching/jumping/falling onto or into an object that could cause injury.
An observer looking under the hood of a car, someone blows the horn, the
observer reacts and bumps head on car hood, sort of scenario.
I'm fairly certain that no one would like to experience a surprise corona
taking place in their home or shop.
It would be very wise to not trust the integrity of a cheap DMM or other
test/measurement equipment on high votage equipment.
High voltages require properly designed test instruments in good operating
condition (not de-rated by by improvised repairs).
The user needs to understand and respect the capabilities of the test
equipment designed for high voltages. Designed for the purpose, not made in
an alley with a lot of inferior components, made to look like a real
instrument.
I've personally seen poor quality meters that have had internal flash-overs
when used on high voltages. I could easily see the outline of the users'
fingers on the meter cases and probes.
I don't know what might be more hazardous than having a corona take place in
one hand with the other hand holding a probe on a high voltage terminal
inside a cabinet full of high voltage connections, with the exceptions of
playing with guns or explosives.
Current passing thru the heart is often deadly.
--
WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html
"Ignoramus20688" wrote in message
...
I have a plasma cutter that is slightly broken (Hypertherm 600 with
cracked torch-to-machine plug). The plasma cutter is 460 v only. (no
kidding). So it sat in my shed for a few years as I had no 460v.
I also have a Lincoln Idealarc DC-1500 welder which I need to test.
(1,500 amp, 1,800 lbs monster). (I want to be clear that whether I can
at all get any life out of it with a 10 kVa single phase transformer,
is not obvious)
This is the prelude.
The story is that one of the mystery devices that I brought turns out
to be what I long wanted to get, which is a 10 kVa ACME Transformer.
It is a multitap thing that allows buck/boost adjustments of a few
percent. It has various taps that I could use if, say, I have 490
volts input and want 240v output. It is nicely laid out inside a
hexagonal transformer box, whose windings are sealed with epoxy.
My first question is, am I correct in assuming that I could use it in
reverse to get 460v from 240, at some reduced kVa. Also, what is the
realistic kVa number I could get from it.
So, my thinking goes, to make it into a 240-460 transformer, I should
allow for some losses and wire it according to the diagram connection
for 480 volts. Then under load, and due to losses, the voltage would
drop a little to 460. Right?
The bonus question is whether this thing could power a 10 HP motor to
make three phase 460v.
--
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