Please Help- best hookup of 3 phase 220v. lathe to 220 single phase welder outlet

[JR49]

This is my first post since my introduction post, so hope I do it correctly. I have a Logan 12" variable speed drive lathe (model 2557VH) I was told it used 220 volt single phase power. I've now found out it uses 3 phase current. Normal mechanical and electrical issues are not a problem for me BUT, I can't seem to get my head around 3 phase. So here's my question. My research tells me the best unit would be a VFD, but the logan already has variable speed drive, and it also has a reversing on-off drum switch. I think your advise will be that the VFD is still the best option, but do I just not use the variable motor speed and reversing options on the VFD, or is it more complicated than that. Again, I am fine with home wiring, and wired my shop for the 50 amp. 220v welder outlet. So just how complicated is this. Please, don't be shy, should I do this myself ? thanks for all responses JR49

 

[hvontres]

Hi-di-ho Neighbor,

For your situation there are three basic options:

1) Use a static phase converter. These will allow you to run the lathe, but at reduced power. The lathe will be wired the same as before.

2) Use a rotary phase converter. This will generate the third phase using an idler motor as a rotary transformer. The lathe still works as before. One advantage of this setup is that if the converter is large enough, you can hook up additional 3-phase machines as they enter your shop.

3) Use a VFD. A VFD will take the single phase input, convert it to DC and then generate three phase ac using internal transistors. The motor MUST be wired directly to the VFD output and not through the drum switch. Alot of times, the original switch is then re-wired as a low voltage input to control the VFD. This option will give you the ability to use soft start to reduce the inrush current when starting and also DC braking to help stop the spindle. One downside to a VFD setup will be that you will probably want to get one for each piece of 3-phase machinery you acquire down the road.

I personally have a VFD on my J2 head bridgeport and love it. I still use the Variable speed drive to change spindle speeds, but I have a nice soft start and I can stop the spindle in less than 2 seconds. In fact I just put a second one on my lathe, and even with a 8" 3 jaw I can stop in about 5s.


I hope this helps,

 

[CluelessNewB]

You can probably use the reversing switch with the VFD but it would be wired to the low voltage control inputs of the VFD, not like it is now. You do NOT want anything between the motor and the VFD except wire.

For a single machine a VFD is probably the least expensive and best option for 3 phase conversion with motors of 3hp or less. The price is about the same as a static converter, you get full motor power and variable speed, slow start and even braking if you want. Having the VFD variable speed along with variable speed drive is just an added bonus.

If you are comfortable with house wiring hooking up a VFD isn't all that complicated. Basically you have single phase coming in and 3 phase coming out directly to the motor. That is everything you "need" to run the motor. Unfortunately the front panel controls on the VFD are probably not what you really want for everyday use. Fortunately most if not all VFD's also have low voltage control inputs for run, stop, forward, reverse and speed control. Most VFD's provide for several different ways to use these inputs.

You will need to program the VFD for the type of external switches you are using and for the parameters of the actual motor you have. None of this is real hard but be prepared to spend a few hours scratching your head when you try to interpret the users manual written in something that almost looks like english. After you figure it all out you will probably conclude it isn't all that bad.

When selecting a VFD the most important thing is getting one rated for your motor. On the motor it should list the voltage and current. Make sure you purchase a VFD rated for a bit more than the current your motor draws, more is fine, a lot more is fine but not required and a waste of money. If your motor is a 200V motor (typically from schools) make sure you VFD can output the lower voltage. (For example the Teco FM50 can't, the TECO JNEV can). I would also look for a sensorless vector drive, not one of the Volts/Hz drives (like the FM50) . I'm not a big fan of the cheap eBay VFD drives, there are better options and they aren't that much more expensive.

Most low cost VFD's are designed to be mounted inside an enclosure. None of mine are mounted that way but I have provided ways to cover the exposed connections. You will also want to keep dirt and swarf out so an enclosure is probably a good idea.

 

[CluelessNewB]

Oh one other thing!

Your 50 amp welder circuit would run the lathe but........

Your VFD will probably use much less than 50 amps. The wire on the input of the VFD will probably be something like #12. You should really have a circuit breaker or fuse protecting that wire with a rating appropriate for the wire size. If the VFD were to fail or the wires feeding it were to short you could be pushing 50 amps through a wire rated only for 20 amps. That makes heat and fire. :yikes:

 

[chips&more]

My vote is to get a VFD. Even though your Logan has vari speed drive you would have the option to find that “sweet spot” in the motor's rpm and vari drive system using the variable frequency…Good Luck.

 

[Ulma Doctor]

my 2 cents
if you have a spare 3 phase motor make a RPC
if not get the VFD

 

[echesak]

I have VFD's on a Bridgeport J-head, Clausing 4914 Lathe and a Doall band saw. It's the only way to go, and many times, the cost is similar to a static converter. Variable speed and reverse is also nice. The best part is that you can program acceleration and deceleration cycles, if you machine coasts to a stop, like mine.

Eric

 

[AR1911]

I recently bought the exact same lathe, and have been scratching my head over the same issue.
Actually, I bought a 11" Powermatic Logan as well, both are 3-phase with 2HP motors.
If you go with a VFD and wish to keep the front panel controls, you basically have to rewire the whole machine. That Logan uses magnetic switches and a contactor. You would need to wire those switches to the low voltage control inputs on the VFD, and eliminate the contactor. This is as I understand it. Not rocket science, but a project I have not yet gotten around to.
I obtained several 1.5KW (2HP) Misubishi E520 VFDs, used, from ebay for about $60. It's hard to discern from the manual if it will run on single phase, but it does.

A friend loaned me a RPC to test it out, which I did last week. Other than finding power plugs to match the RPC, it was plug and play. I can certainly see the attraction, and I may try to buy this RPC from my friend.