3ph vs 1ph, or transformer + converter for lathe

[LD1]

Another question regarding some 3 phase equipment.

Along with the twistair compressor I got....I also acquired a old.monarch 16x54 lathe.

I have a junk (by comparison) clausing 1500 now in the shop....but it's actually a friends and at some point he is gonna want it back. So I got this monarch.

Dug down to the motor hoping it was a dual voltage motor.

No dice. High voltage only. So no way to currently run off phase converter.

Unlike many lathes that is specialized motors....this one is just a standard off the shelf 184t frame...1750 rpm....5hp. But 460-480v only.

So I basically think I have 3 options.
1. Buy a dual voltage 3ph motor so I can wire for low voltage and run off converter.
2. Buy a single phase 5hp and forget using my converter.
3. Leave lathe as is and buy a 6kva step-up transformer.

Spending about 5 min googling, it appears if I look hard enough, all 3 options can be sourced under $500. But I haven't don't a whole lot of looking.

So aside from cost...any advantages to one over the other?

Seems the simplest is just gonna be go single phase and forget the converter and forget the added wiring of a transformer or converter.

What do you guys think?

 

[Rustyiron]

I think I'm going to watch this one.
I have a true "cold saw" that was from Canada, (475v 3ph) taking up floor space. The motor looks to be specific as it has a built in rt angle worm gear drive that serves as the motor mount.
I get very confused with these electrical problems

 

[mikester]

Another question regarding some 3 phase equipment.

Along with the twistair compressor I got....I also acquired a old.monarch 16x54 lathe.

I have a junk (by comparison) clausing 1500 now in the shop....but it's actually a friends and at some point he is gonna want it back. So I got this monarch.

Dug down to the motor hoping it was a dual voltage motor.

No dice. High voltage only. So no way to currently run off phase converter.

Unlike many lathes that is specialized motors....this one is just a standard off the shelf 184t frame...1750 rpm....5hp. But 460-480v only.

So I basically think I have 3 options.
1. Buy a dual voltage 3ph motor so I can wire for low voltage and run off converter.
2. Buy a single phase 5hp and forget using my converter.
3. Leave lathe as is and buy a 6kva step-up transformer.

Spending about 5 min googling, it appears if I look hard enough, all 3 options can be sourced under $500. But I haven't don't a whole lot of looking.

So aside from cost...any advantages to one over the other?

Seems the simplest is just gonna be go single phase and forget the converter and forget the added wiring of a transformer or converter.

What do you guys think?

I'm not clear here - do you have 3 phase already in the shop? If you do then buy a step up or down transformer. I'd take 3 phase over single phase any day.

If you don't have 3 phase then I'd buy a new single phase motor since you don't appear to have the correct voltage for the machine. It's cheaper than buying a VFD and transformer for that motor.

I'd recommend to go VFD over phase converter on the lathe unless you already have the 3 phase converter.

 

[LD1]

Not sure how what I wrote was confusing....but here goes again.

I have SINGLE PHASE 240v in the shop.
I have both a 10hp and a 15hp rotary phase converter. I am currently running a bridgeport 3hp mill an a clausing 5hp lahe....BOTH 3 phase....off of rotary converters.

I got a new lathe. The motor is NOT a dual wound motor. Meaning it is NOT a 230/460 motor. It is a 460v motor only. So NO, I cannot run it off my 240v phase converter as it sits now.

My options are
1. Buy a 240v SINGLE PHASE motor. Going to cost me ~$350. And will have to do sone rewiring of controls, because currently the controls are powered off a xfmr from the original 480v input. But no need for a converter after this swap.

2. Buy a 230/460 THREE PHASE motor. Wire for low voltage, and run off one of my existing phase converters. Would still need to do the same re-wiring of controls as if I went with a single phase motor. I can get one of these motors for $200

3. Buy a transformer. To step up the 240v output of my phase converter to 480v. Also cost about $300. No need to rewire anything with the controls.

I know the simplest and probably best long term is to just buy a single phase 5hp motor. 3 phase stuff is cheaper.......and more efficient....but dont know if the "more efficient" part applies when running a rotary to power it.

The benefit of 3 phase is less amps = smaller wire. But its not exactly like a 5hp 240v motor pulls a ton of amps anyway.

 

[Budweiser John]

My opinion, if you already have a phase converter, swap out the motor for a 3ph dual voltage motor and hook it up on the low voltage.
From a future resale perspective the choice might be weighted to repowering with a single phase motor.
Personally, I would stay away from a transformer option as they are expensive, generate heat, and suck up a lot of juice in their operation.
B. John

 

[buickanddeere]

Transformer and a three phase VFD . Gives torque control, braking and reversing . Later other 480V three phase equipment can be purchased and used .

 

[LD1]

Transformer and a three phase VFD . Gives torque control, braking and reversing . Later other 480V three phase equipment can be purchased and used .

Transformer + VFD significantly adds to cost

If I wanted VFD control I'd sooner swap to a dual voltage 3phase motor (probably about the same cost as the xfmr) then I'd fun a low voltage VFD

 

[RNeumann]

I’d use a step up transformer for your 240v split phase (it’s technically not single phase 240v in the USA) to get your 480v. Changing motors and controls only snowballs when you need replacement parts etc- you are just making extra work for yourself!
Transformers and phase converters are a simple set and forget device that will be trouble free for decades.

 

[LD1]

Controls are just 120v.

Don't plan on changing controls.

Just where they source power, which is currently with a small transformer off the 480v supply. So I just have to change where they source power. Get rid of the transformer that is used.

Probably just source it from the 120v wall plug.

Yes it involves a little rewiring. But components, and future needs shouldn't change

 

[marchanna]

I would keep it simple and just get a single phase 240 motor. A 5hp motor drawing peak is only going to draw 15.5amps, so you can plug it into any 240vac 20amp receptacle. Makes for relocating in the shop pretty easy. I’m assuming this is just hobby stuff, given that you’re humming and hawing over a few hundred dollars.