single 230 to three 440

Local selling 20 x 72 1948? believe Monarch lathe, problem is it has a 440 three phase.

What is the best way to convert 230 single to 440 Three.

I already have one 7hp RPC from 230 single to 230 three phase.

Most Monarchs are 230/460 and employ a reversing magnetic motor starter which can easily be rewired from 460 to 230 volts. (The coil is usually 115, and is supplied from a 460/230:115 control transformer).

There are only two heaters on these machines, in the A and C phases, and replacements can be difficult to find.

Check the NEMA Size, and compare that to the motor HP and be sure you can effect the conversion without exceeding the rating of the starter.

Monarch usually claims these machines cannot be rewired, but the wiring diagram shows how this can be accomplished.

What is not shown is the starter Size, and the wiring gauge, both of which must be taken into account.

Thanks peter, but that is way over my head, you would be lol right now if you could see my face.

What does that mean to me, who can do this service for me, can I replace the motor with a 230 three phase or it that way over my head also.

"What does that mean to me, who can do this service for me, can I replace the motor with a 230 three phase or it that way over my head also."

The motors are usually nine-wire 230/460, but later ones can be 208-240/480.

Anyway, you use the wiring diagram on the motor's nameplate to rewire it to 230, then you rewire the primary of the control transformer to 230, and you are good to go except for the starter's heaters, which have to be obtained just for the particular starter (there are many possible starters, and even more possible heater ratings). You select these from the motor's FLA on 230, and then you replace the heaters.

Of course, it helps considerably to have three-phase already installed.

OK I just went through this with a 14x40 TURRET brand looks pretty much identical to a turnmaster anyhow it had a two speed motor that was not rewirable for 230.
So I came up with two possible ways to go 1. Get (buy) a 230-440 single phase transformer (about $500)and build another RPC this would involve higher voltage capacitors and such and another motor. Or just buy a 3 phase 220-440 transformer($800w/shipping from MSC) and run it from my existing 7.5hp RPC. I chose the second option as I didn't have time to scrounge the components which I am sure could be assembled for little money and a lot of patients

Translation...

Titan-

What Peter is saying, is that it is very possible to convert your machine to 230.

Your response is to the effect that you're not thinking that you're capable of doing the conversion... and that's an admirable admission.

What you need to do, is find a local industrial electrical guru who'd be willing to do the task for you... I'll bet that if you look up a bunch of other local machinery-type guys, you'll find at least ONE of 'em who understands the electricals of these things and can do it for you for a reasonable case of beer cost.

Here's what has to be done:

Find the motor. On the motor is a little diagram that indicates wiring connections for LOW (230v) and high (460v) wiring. Open up the motor wiring-access panel, look at all those wires- they all have little number tags. Disconnect and switch all the motor wires around to match the LOW diagram.

Next, find any OTHER devices (coolant pumps, control transformers, etc) and do the same- they'll usually have labels.

Next, find the motor-starter unit. It usually has at least one button (RESET) or even a pair of START/STOP buttons hooked to it... and inside is one or more iron things that look like relays. There's at least one coil in there, oftentimes more, and one or more 'heaters'. These heaters... there's one type required for 480 (high voltage, low current) and one type required for 230 (high current, low voltage). These things get hotter as more current flows through 'em... and when they get so hot, they shut the machine down. Of course, in a low-voltage motor, the current is higher, so they trip too soon... which is why we're changing 'em.

Now, after reading my explanation, pop off the covers and take a look... you MAY decide that it's not that complicated... but at least you'll know what needs to be done.

If you're not up to doing it yourself, find another local machinst-type, or a guy who's been an industrial electrician for years... someone who has set up machinery in an industrial environment.

A third solution for UNFKR...

The third, and much less expensive solution for UNFKR's situation (which is NOT the same situation as this thread), is to find a 10kva 480/240v single phase dry transformer (surplus ~$50) and a surplus 10-15hp 480v VFD of mid '90's technology (surplus ~100) and feed the transformer backwards (240 in, 480 out) to the VFD.

Cheaper than solutions 1 and 2, much smaller, quieter, and much better result.

Thanks guys, The lathe that I was looking at ended up to big, its really just for hogging off material. The motor did not have a name plate on it.

I've posted it on the for sale thread if anybody is interested.

Dave, thanks for clarifying.
Some things I know how to do and some I do not. Rewiring a motor I do not.

Good news if somebody does by the lath it comes with a 230 three phase to 440 transformer. They want 2500 for it and will help load.


Thanks for the help
Michael