Folks,
I have a line on this three phase transformer. I want to step up 220V
three phase out of my 15 HP RPC to 480V so that I could power up my
recently acquired Brown & Sharpe #2 vertical mill made in the 50's.
There are many here who are in the know on industrial electrics. Can
I please have a quick review on the specs of this transformer in the
link below and verify for me that if wired 220V 3 phase on the
secondary, I could get 480V 3 phase out of the primary? Thanks.

http://www.jeffersonelectric.com/cgi...-000&query=423

trg-s338 wrote:
...if wired 220V 3 phase on the
secondary, I could get 480V 3 phase out of the primary? ...

Yes & no. 1st - if you actually have 220 & not 240, then no. But you
probably have 240 (most single phase is 240, I dunno about 3 phase). If
so, then you could use the 504v taps & get 450 - 475v out. This is
because of core losses. I'm assuming 5 - 10%, but that's a guess.

Good luck,
Bob

trg-s338 wrote:
Folks,
I have a line on this three phase transformer. I want to step up 220V
three phase out of my 15 HP RPC to 480V so that I could power up my
recently acquired Brown & Sharpe #2 vertical mill made in the 50's.
There are many here who are in the know on industrial electrics. Can
I please have a quick review on the specs of this transformer in the
link below and verify for me that if wired 220V 3 phase on the
secondary, I could get 480V 3 phase out of the primary? Thanks.

http://www.jeffersonelectric.com/cgi...-000&query=423

Looks like it sure would work. You have plenty of taps to choose from.
Probably, assuming you really have 240 V service, the 480 V tap would
give you 480 V out, +/- a percent or two. Why not set up the idler
motor to run off 480, and use a single-phase step-down transformer to
feed it 480 from your 240 mains. Note that a 15 Hp idler would draw
about 50 A reactive from 3-phase mains all the time it is running. I
don't know how much worse that gets running it from single phase, but it
almost certainly goes up. Without a big capacitor bank, the bad power
factor might put out your lights unless you have a 400 A service, or
have very little other load on a 200 A service. If you have to buy this
transformer new, you really should look at a used 480 V VFD on eBay.
The 480 V units go cheap. Then, get a 240:480 single-phase step-up and
you are set. No loud noise, no horrible power factor, no energy waste,
and you get variable speed, too!

Jon

On Wed, 08 Jul 2009 15:29:57 -0500, Jon Elson wrote:

trg-s338 wrote:
Folks,
I have a line on this three phase transformer. I want to step up 220V
three phase out of my 15 HP RPC to 480V so that I could power up my
recently acquired Brown & Sharpe #2 vertical mill made in the 50's.
There are many here who are in the know on industrial electrics. Can
I please have a quick review on the specs of this transformer in the
link below and verify for me that if wired 220V 3 phase on the
secondary, I could get 480V 3 phase out of the primary? Thanks.

http://www.jeffersonelectric.com/cgi...-000&query=423

Looks like it sure would work. You have plenty of taps to choose from.
Probably, assuming you really have 240 V service, the 480 V tap would
give you 480 V out, +/- a percent or two. Why not set up the idler
motor to run off 480, and use a single-phase step-down transformer to
feed it 480 from your 240 mains. Note that a 15 Hp idler would draw
about 50 A reactive from 3-phase mains all the time it is running. I
don't know how much worse that gets running it from single phase, but it
almost certainly goes up. Without a big capacitor bank, the bad power
factor might put out your lights unless you have a 400 A service, or
have very little other load on a 200 A service. If you have to buy this
transformer new, you really should look at a used 480 V VFD on eBay.
The 480 V units go cheap. Then, get a 240:480 single-phase step-up and
you are set. No loud noise, no horrible power factor, no energy waste,
and you get variable speed, too!

Jon

Good answer both gents.

Where does the OP live? I have some transformers available....

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