First off, let me apologize for starting a new thread when there may be a discussion on this already. :cheers:
We just got a 460 Volt 3 Phase engine lathe (geared head handle puller - not CNC). We are not nearly as ignorant about our power problem as we were when we bought this beautiful old machine. Where we are at now is trying to decide if there is going to be any way to hook her up without pulling the motor and taking it to somebody who we hope knows what he is doing. We tend to think that will be the inevitable next step.
The motor is single rated 460 volts 3-phase 11amps 7.5hp 1800 rpm. It is not dual rated and we can not find a wiring diagram anywhere. The motor has three wires coming out of it, and according to Auburn Armature Inc (whose sticker is on the newly rebuilt looking motor), they said if we had three phase 460 volts going in, we could just connect the power and it would be fine. Any thing else and we have problems to solve.
Question #1 Why 460 volts and not 480 volts?
We saw a phase converter that can take take our 220 volt single phase power and turn it into 415 volt 3-phase, such as the Eurotech. But as far as we know, that won't work. That is what they use in Europe and Australia. They are very expensive too.
Getting three phase power from the utility company's pole fifty feet away would be possible, but cost somewhere around $15,000 (we checked). That is not going to happen.
Getting 240 volt 3-phase seems to have several options under static, rotary and vfd. It seems we would still need some kind of brown out and/or phase fluctuation protection as well. We definitely prefer to somehow obtain balanced three phase power, or just buy a new 7.5hp 1800rpm single phase motor, but still have the problem of adapting the shaft to accept the spindle pulley belt drive. The latter may be the cheapest way to get the machine running, but more costly operating in the long run - motor life, Kw usage. We are not going to be running this thing all of the time anyway.
There are a couple of motor re-builders not too far from home. And they seem to be willing to venture to say that they can rewire it for 240 volt 3-phase and give ball park cost estimates between $600 and $750. Seems a little pricey to me. Together with a compatible phase converter, that might be the way to go.
Is there anyone out there who can confirm we need to pull the motor (it is huge and heavy) and take it to a motor re-builder to adapt it for 3 phase 240v operation? If so, how can we be sure it will be right when the motor plate clearly identifies it as 460 volt, not 480 volt? And finally, how would we decide on a reliable phase converter that would protect the motor and not break the bank? We really do not care if we end up with less than full horse power. But for speed and feed calculations, we do want to make sure it will run at 1800 rpm. (Question 3# what controls the motor rpm? )
Thank You,
Renee B
Ps. If we get this much done, will electricians be able to break out the wiring for the coolant pump motor without another big fuss.