I just bought my first lathe, which is a Rivett 1020S, and I'm
obviously excited and ready to get it running. The motor is a 3-phase
5HP 240/480V and it is currently wired for 480V.
I plan to setup a phase converter using at least a 3-phase 240V 10HP
I've never setup a transformer to increase the voltage from my
converted 3-phase 240V to 480V and so I'm seeking advice on this.
Instead of the 10HP 3-phase 240V motor for the phase converter, will I
need to increase the HP any? Does this motor need to be a 240/480V?
Thanks in advance for any advice.
Mark, you made me confused, why don't you rewire the 240/480 lathe
motor to run off 240V? That would be easiest and would not require
buying a bulky, and costly transformer, as well as eliminate
When I open the power panel on the end of the lathe I see the 3 wires
for the service power... but those wires hook into what looks like a
fairly complex power panel (I think it's the original Vari-Drive), and
from that it leads to the motor. I've never rewired a motor from 480V
I would prefer doing this the simplest way possible and so wiring 240V
would be great if I knew how to do it. Thanks.
We need the motor data to help you. Someone here should be able to
tell you how to connect the motor for 240 volt operation. If the motor
is dual voltage then it makes sense that the control electrics will
also work with either 240 or 480 volts. Anyway, if you have 240 volt
service, then it will be lots easier and cheaper to build a 240 volt
rotary phase converter and change the internal motor connections. It's
not like you need to remove the motor windings and have it re-wound.
The motor will probably have 9 wires that can be connected two
different ways for either 240 or 480 volt operation. A common wiring
configuration is having the wires numbered 1 through 9. For 480 volt
operation the wires would be connected thusly: 6+9, 5+8, 4+7, with
wires 3, 2, and 1 connected to the power. For 240 volts the
connections are: 6+5+4, 9+3, 8+2, 7+1, with the power again connected
to wires 3, 2, and 1. Of course, since this is a three phase motor,
swapping any two of the three power wires will reverse the motor. I
bet someone here has the actual wiring specs for your lathe.
That model has an electrically driven speed control and an oil pump
(which may or may not have its own motor). Those may have to be
rewired as well -- but they probably don't operate on 480 volts now
and may already be wired for 220.
This is entirely doable. I have a RPC giving me my 240 3 ph. It is
wired into a 240V distribution panel and a transformer. The
transformer takes 240 3ph in and 480 3ph out. Then I go into a 480
distribution panel. The cost of the used transformer, panel and wiring
was about $300.
I had one piece of equipment that was impracical to convert to 240 from
480. The coils for the starter would have had to be changed,
everything else switched, so I wanted to run it on 480. 2 other lathes
were 480 only. I can run smaller wire and the large motors start
easier on high voltage.
This was especially proven to me on my air compressor. On 240 I could
not start it when cold. On 480, the compressor starts much easier and
Now I have the option to run most equipment and not have to worry about
Thanks to all for writing in and helping. I've been working tons of
overtime hours and so I had to wait for the weekend to look at the
I looked at the wire diagram on the motor and it's exactly as Eric
stated. I only see lables for wires 1, 2 & 3 from my motor and so I'm
going to try and figure out which wire number belong to the others.
The motor has the following listed on another plate:
5 HP Constant Duty
Let me know if you need any other information. I've taken some
pictures but I misplaced my cord to load them into my computer. I'll
find it and load them for you to see close-ups of stuff.
Thanks again to all for your help.
According to Mark Main :
[ ... ]
Hmm ... what media in the camera? CF, SD, one of the others?
There are quite inexpensive USB devices in your local computer store
(I've found mine in Micro Center, FWIW) which will allow you read the
cards directly into the computer without the camera being involved. It
is much faster than doing so from the camera, and it is less strain on
the camera's battery as well.
You do know to post the images to the dropbox, not to the
newsgroup, I hope? The instructions can be found on the dropbox.