[AMPS] Re;Xfmrs

[Peter Chadwick]

Merit  W6NQ says:

>I wonder if it might be best to reverse pri & sec to the mains.
>(LV to the secondary side.)
>You are only going to need a few volts from the variac with the
>ammeter shorting the opposite winding.

In that case, the rms current measured on the amp meter must be multiplied
by the xfmr ratio

eg a 220 to 2200 volt xfmr and you want to test at 1 amp in the HV winding:
then if reversed, you need 10amps in the  220 volt winding and through the
amp meter

>(I blew a meter once doing this test when I was careless.)

The 'famous' multi-meter over here is made by a company called AVO. The AVO
meters have gone through various models:they are bigger and chunkier than
SImpson VOMs, but the great thing is that they have a mechanical cut out
which prevents damage if you badly overload it. New, they're  around $500
now, but you can get them for about $60 -70. They have a big advantage over
DMMs - they give the same readings either in or out of an RF field! Like all
these things though, common sense saves a lot of problems.

However, the tale of the lady in India trying to get some electrical work
done comes to mind. Pestered by questions from the electrician, she said
"You know what I want, now use your common sense".

The response was " Madam, common sense comes from God: I only had a
technical education".

There's a moral there for all us techies.......................


73

Peter G3RZP



--
FAQ on WWW:               http://www.contesting.com/ampfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm