On Tue, 26 May 2009 23:25:33 -0700 (PDT), trg-s338
wrote:

On May 26, 10:00*pm, Gunner Asch wrote:
On Tue, 26 May 2009 21:14:32 -0700 (PDT), KD7HB
wrote:



On May 26, 5:18*pm, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:
Gunner Asch fired this volley :

How about a 480 step DOWN transformer and simply turn it around
backwards?

Due to core losses, copper losses, et. al., it won't work at the 2:1
ratio in reverse.

LLoyd

Hi, Lloyd.
The voltage ratios have to be the same, either direction, as they are
physical quantities(turns counts). What doesn't work it the KVA
rating, according to the electrician that installed the transformer to
operate our convection oven for soldering circuit boards. He said to
de-rate the KVA 10%. We have been running a transformer backwards to
get 480 from 208 for about 4 years, now. 24/7.

Paul

Ayup. I always calculate -20%

Gunner


If a step down transformer is used in reverse, how would one ground
the secondary (which now acts as primary)?


You mean besides using that big green tab located on the frame of the
transformer?

Or something else?

You do realize we are talking about 3ph transformers...right?

Gunner

"Lenin called them "useful idiots," those people living in
liberal democracies who by giving moral and material support
to a totalitarian ideology in effect were braiding the rope that
would hang them. Why people who enjoyed freedom and prosperity worked
passionately to destroy both is a fascinating question, one still with us
today. Now the useful idiots can be found in the chorus of appeasement,
reflexive anti-Americanism, and sentimental idealism trying to inhibit
the necessary responses to another freedom-hating ideology, radical Islam"

Bruce C. Thornton, a professor of Classics at American University of Cal State Fresno