On Mon, 09 May 2011 23:56:30 -0500, Martin Eastburn
wrote:

Gunner -

There are two methods -

make the input 246 volts drop across two transformer windings - and
one goes to nothing. But the best is on the secondary.

Have your main transformer attached.
In parallel to it - e.g. same breakers and same on/off.....

The secondary is '24v' AC. The wires are phase generating.
One when put in series with the main power secondary - adds - and you
get 280v or something. Swap the 24v wires (or the primary if easier)
and you get 220v across both.


The secondary current has to be equal or more than that of the
big transformer secondary.

5700 volt-amp = wattage (no phase angle)
5700W/220V = 26 amp ? maybe 30.0 amp. So the 24v transformer has to
have a 30 amp or more secondary current.

I can do a drawing for you if you need. I do this method on my 3-phase.

Martin

Ive got it Martin, but many thanks. It rained yesterday, and I had to
load that old Gorton mill in the rain when Id planned on digging out the
10 or more transformers that Ive got scattered around on the shelves out
back. Now that I know how to do it..Ill do it this coming weekend after
I get back from LA..where Im headed in an hour or so. Just have to load
the truck and be on the road.

I know Ive got some that will be big enough to handle 30 or so amps.

Many thanks!!

Gunner




On 5/9/2011 2:55 AM, Gunner Asch wrote:
On Mon, 09 May 2011 00:06:29 -0700, Gunner
wrote:

On Mon, 09 May 2011 01:19:57 -0400, "Michael A. Terrell"
wrote:


Gunner Asch wrote:

Ive got a 5hp PC3 vfd running my Gorton MasterMill.
The top end voltage it is supposed to run on..is 230vts + about 5 volts
It will run down to 200 volts.
Im running it on single phase, been doing it for years.

Now the power company has increased my 220 single phase to about 249
volts and when I try to start it..I keep getting OverVoltage Alarm.

I cant get the power company to change the tap down to a normal voltage,
let alone 220 volts

How do I (cheaply) transform high voltage down 14-29 volts ac?

Id hate to loose the VFD on this mill and have to run it off a RPC
(which also puts out higher voltages)


How much current do you need? A simple buck transformer will do the
job, as long as it's secondary can handle the current.

I believe its 5.7kva

Gunner

Ok...Im going to look REALLY stupid here. Sigh..blame it on the stroke.
Or not..shrug

Ive got a BUNCH of 120/240 transformers..all marked 120/240 12/24

So if I wire one up to 240..does it mean that it will REDUCE the voltage
-24 volts?

Or is the output 24 volts?

I see I havent gotten everything back from the stroke....sigh

Gunner


--
"If I say two plus two is four and a Democrat says two plus two is eight,
it's not a partial victory for me when we agree that two plus two is
six. " Jonah Goldberg (modified)