[Test-Equipment] Isolation transformer

[Rasputin Novgorod]

> >  From: "Rasputin Novgorod" <priapulus at yahoo.com>
> > I have a small 115vac Isolation transformer that I power
> > projects with, expecially transformerless ones,
> > for safety's sake. How do I test it, with an ohm meter,
> > to know that it is wired correctly and safely?

Thank you for all your responses. I'm very grateful
to everyone who replied with advice. To clarify, there 
were two isolation transformers; I was concerned with
the small bench one. The reply consensus seems to be:

> 1) continuity between input and output grounds.
> 2) no continuity between either output lead to
> output ground.

Add to that: 3) no continuity between either input 
lead to either output lead.

-----------------------------------------------------
My second transformer was a large Sola 
Auto/Isolation transformer which caused Inspector 
grief.

> First, let's establish what kind of transformer you have.
> An "auto/isolation" transformer cannot exist; either it
> is an autotransformer which, by definition has no
> isolation, or it is an isolation transformer
> which, by definition cannot be an autotransformer.

The maunal for the transformer would disagree, unless
I'm reading it wrong. There are no electrical connections
between primary and secondary, except ground. If I'm
reading it wrong, please correct me; manual here:

http://www.ontariorocks.ca/temp/Sola%20CVSManual.pdf

I have a room, which is my Ham, electronics hobby shack.
I invested a lot of effort and money to build a very
quiet and robust single point grounding system for the
room for antennas, lightning and safety. A much quieter
and better ground than the pipe clamp in the cold water
pipe at the electrical service entrance.

I planned to use my big transformer to cleanup and
isolate the hot, neutral and ground connections
from the utility so the dirty utility ground didn't
contaminate my nice quiet shop ground. 

But that would be against the code... When I 'scoped
each ground the utility ground was noticably noisy.
However, when I bonded the two grounds together (at the
isolation transformer) my ground pulled the utility
ground down to full-quieting so I left it legal. (That does
leave me with the problem of my Single-Point grounding
having two grounds).

The inspecter wanted the pri and sec grounds and neutrals(!)
all bonded together. I argued the secondary neutral
should not be bonded to ground or there would be no
point to the transformer.

This used Sola 15 amp, 230vac protects all my equipment 
from rfi, sags, surges and indirect lightning hits;
not bad for a $75 purchase at a Hamfest. It took two
of us to carry it!

Sincerely
/b


		
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