Does anyone know where to find a surplused 240V to 480V 3 phase step
up transformer at around the 15 Kva range. I need one to power off of
my 15HP RPC to run my 480V 3 phase B&S Vertical mill. Los Angles,
Orange County, Inland Empire or San Diego area would be great. Don't
want to pay shipping for this weighty item ya know. Thanks.
trg-s338
Gunner Asch fired this volley in
news: snipped-for-privacy@4ax.com:
Due to core losses, copper losses, et. al., it won't work at the 2:1
ratio in reverse.
LLoyd
Odd..I do it regularly.
Shrug...
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
Gunner Asch fired this volley in
news: snipped-for-privacy@4ax.com:
What, at no load? Gunner, I worked for a couple of years in the
design and testing lab of Florida Transitron. I know just a bit about
them, and have made many from scrapped parts of others, since.
A 2:1 step-down transformer is NOT wound precisely to 2:1 ratio,
unless it's: 1)so lightly loaded as to constitute virtually no load at
all, or 2) working at much higher frequencies than 60Hz (and even then
loading plays a factor).
I know you don't understand that the secondary has resistance, or that
the core has hysteresis losses; but they do.
(Gunner... again!)
LLoyd
David Lesher fired this volley in news:gvi3nb$2i8$1
@reader1.panix.com:
Ignorance doesn't make it work properly.
Sorry, but you and Gunner are reading off the same page, and it's not
even in the electronics book.
LLoyd
Or 3) if it's in the size range being discussed here. The turns ratio
is tweaked in smaller dry-type transformers, but is equal to the
voltage ratio in larger units. The transition point varies between
manufacturers: Acme compensates single phase xfomers below 1 kVA and 3
phase units below 15 kVA; Hammond drops the compensation at 3 and 6
kVA.
You do need to pay extra attention to the actual internal connections
in 3 phase xformers when reverse connecting.
Well, I got an A in EE421; and was proud of it. Granted it was 20+ years
ago, but last I heard Maxwell, RH rule and that guy Thevenin still hold
to this day.
Sure there are losses, all kinds of losses.. We got copper resistance
losses, we got eddy current losses, you name it. But I don't recall any
reason they don't apply no matter which way you go. Can you cite a source
to back you up?
Blink blink...so none of the transformers Ive installed are working?
Damn....bunch of miracle machines!!!!!
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
Yes you do. And you have to adjust the voltage bars carefully to insure
the proper output voltage.
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
google "using a step down transformer in reverse"
Results...96,800 hits
Shrug, believe what you wish to.
You are still wrong. Shrug.
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
snipped-for-privacy@4ax.com:
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
Easy thar, fellas, this ain't politics. All of you are right.
Xfmrs with smaller VA or KVA ratings are designed with a bit of fudge
factor so they'll deliver rated voltage at rated load in spite of
droop at rated load. Larger xfmrs are designed to have negligible
droop at rated load because to do otherwise would result in
unacceptable inefficiency and heating.
innews: snipped-for-privacy@4ax.com:
Ayup. I always calculate -20%
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
innews: snipped-for-privacy@4ax.com:
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
Gunner Asch fired this volley in
news: snipped-for-privacy@4ax.com:
You just confirmed my original statement. You never mentioned it's
being a stepped secondary -- just "2:1 step-down".
LLoyd
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