5-7hp lathe on 230 1 phase help please

Hi Folks,

I am in need of a bigger lathe in our shop. power here is limited to 220v single phase (100 a max). When I installed our Phase 1 Bridgeport vert mil (2hp), I used a Teco (Westinghouse) VFD with wonderful results. My problem now is that I have located a Southbend Nordic 15 that would be perfect for my needs but it has 5 HP motor (from the owners manual information) and I have seen other info (on the web) that indicates that the motor could be a 7.5hp.

So far, I have been unable to find a VFD that will drive the 5hp 3 phase motor with a 220 v single phase input. I doubt I will ever need all the HP (I need the spindle through-hole diameter).

Are there VFDs available to meet this need? Is there a better alternative? I do not need the variable speed for the gear head lathe.

Thank you for any guidance in this matter. Happy new year!

Rick
Asheville, NC

AC Tech SCF-series 5 hp drive

NC Rick said:

So far, I have been unable to find a VFD that will drive the 5hp 3 phase motor with a 220 v single phase input.

Click to expand...

I have an AC Tech SCF-series drive on my 5 hp Monarch 10ee, and it works great.

This drive is rated for full (5 hp) output with single-phase 220v input.

However, this is the highest hp drive you can find with that spec. If you do indeed have a 7.5 hp motor you'll have to go to a drive rated 15 hp AND rated by the manufacturer to operate with single-phase input.

- Leigh

"However, this is the highest hp drive you can find with that spec."

Perhaps from AC Tech.

Polyspede is a manufacturer of VFDs which are single-phase input, only.

But, all have three-phase output at horsepower ratings well into the high integral HP.

I personally own several TECO/Westinghouse FM100s, and I like those.

However, for more than 5 HP, I would go with Polyspede as these do not have to be derated at all as these are single-phase input, only.

http://www.polyspede.com/acdrives.html

I am not affiliated in any way with Polyspede or any other manufacturer, distributor or retailer of VFDs. Or of anything, for that matter.

peterh5322 said:

Polyspede is a manufacturer of VFDs which are single-phase input, only.
But, all have three-phase output at horsepower ratings well into the high integral HP.
However, for more than 5 HP, I would go with Polyspede as these do not have to be derated at all as these are single-phase input, only.

Click to expand...

Hi Peter,

I've seen the Polyspede drives on the internet, though I've never used one.

I think they're expanding their product offerings continually. When I looked at theirs a year of so ago they maxed out at 5 hp, but they've probably added new versions since then.

Thanks for the updated.

- Leigh

Rick,
Hitachi X200 series inverters will accept single phase input and give you three phase out for your lathe. As Leigh notes, you will have to double the inverter size to accomplish this.

This is a factory approved method with instructions to back it up. I just did this on a lathe I purchased and the cost for the 10 HP inverter was $680 dollars.

The lathe I purchased is a 17" model and came from the factory with a 7.5 HP motor. I felt the motor was too large for my use plus the 15 HP inverter was almost a thousand dollars. I had access to a nice 5 HP for free so I installed that and the less expensive 10 HP inverter and am very happy.

I purchased the Hitachi VFD on eBay from 'Driveswarehouse'.

Stuart

"I think they're expanding their product offerings continually. When I looked at theirs a year of so ago they maxed out at 5 hp, but they've probably added new versions since then."

That brand, Polyspede, offers VFDs with ratings to 100 HP, and above.

Also offered are dc drives.

But, if I had, say, an EE1000 with a failed drive, I might go with a 20 HP Spedestar and an ac motor.

Unfortunately, they are using the perhaps incorrect term "phase converter drive", to describe their single-phase input, only, product.

Sure, phase conversion is implicit in such a drive, and I suppose a single-in/three-out drive is indeed a "phase converter drive", but it is also a variable frequency drive, too.

There are now more than a couple of single-in/three-out options at the 5 HP level, without derating, but above 5 HP derating is usually required.

Not with Polyspede drives, however, most of these are single-in, only.

NC Rick: I have a 15" Nordic with a 7 1/2 hp motor (I've also seen several with 5 hp's). I power mine with a Mitsubishi Freqrol FR-A220E 5.5K (7 1/2hp) VFD on 240v single phase. I think the Freqrols up to 7.5k (10hp) can be powered from single phase. I was concerned about the single phase power, but have taken a 0.200" cut in 4" CRS at a pretty good feed rate with no problem. Not all VFD can be powered by single phase. I also have 2 mills, 2 band saws and a drill press powered by 1.5K (2hp) Freqrol's on 240v single phase.

The reason I went to the VFD on the Nordic was because I was having troubles with one of the electric clutches and wanted to modify the machine by removing the 3 clutches. Replacement clutches are no longer avaiable. The VFD then provides the spindle accel/decel. Removing the clutches was quite a task, and I had to make a replacement shaft. With the VFD and without the clutches, the motor does not run all the time - only when I start the spindle.

I described this modification sometime back on the Southbend Lathe forum. A guy from Tasmania, Australia, with a 15" Nordic was interested in what I did and the old clutches. I gave him the clutches (he paid shipment).

Howard
Clinton, TN

polyspede

I have a 7.5 HP lathe running on single phase via a spedestar PC 1-75 (230 1 phase in, 3 phase out rated 7.5 Hp. Works great but, in 2 years back twice,first time free ( if you dont count $70 shipping). It is due back from second repair this week (after a bit over a month) with both way shipping, about $270. Just my experience. Results may vary. It is properly connected etc.

Thank you folks SO much! This really helps. I am set to have a rigger deliver the lathe on Monday morning but I do still have opportunity to nix the deal. I was close before reading your cogent responses.

At first look, the Hitachi drive from Drives warehouse looks perfect (at under $300). I looked at the polyspede site and it looks like they have whatever I would need. I could not find a discounting outlet for these.

If I may take advantage of the knowledge that you folks have I have more questions - comments.

The Lathe I am looking at / getting was fused to 15A leading me to think that the owners manual 5hp is correct. The motor is buried in the cabinet so I did not see a motor plate. On my Mill, I sized the drive right to the motor (2 HP) and all is fine except when I try to use a steep deceleration rate, where the unit will trip out. (I think I had to limit the deceleration to 3 seconds. I did not purchase the add-on brake resistors which I think may solve this "problem". For certain operations, I would like a quicker deceleration.

If I can, I would like to avoid this deceleration issue on the lathe. I see that the Hitachi has regenerative braking which I assume puts the energy back to where it came. I have to admit that my knowledge of these systems is being taxed here!

Can you guys explain what you refer to as "de-rating"? A friends 16" Sb lathe uses a 3HP motor and I have not seen problems with HP when using that.

My present lathe is a single phase Rockwell with a belt sheave vari-drive and no brake so I have no experience with geared head lathes.

Thank you again, I am encouraged!

Howard, I typed the first reply while you posted so I just saw this. I would love to talk to you about the Nordic. Everything works on this one that I am looking at and it seams really low hours, the ways look near new and the factory paint is in fantastic condition. I heard about clutch problems but hoped to avid them since mine will not be run in a production environment. We work on motorcycle suspension and build tools, one-off parts and use the lathe to fix components.

It sounds like I do not need to worry about accel/decel ramps with the geared head lathe. I did not realize that the motor is always running.

Is the fact that the one I am looking at has 15a input fuses indicitive to this not being a 7.5 HP version?

I am wondering what the de-rating has to do with this issue too.

"Can you guys explain what you refer to as 'de-rating'?"

Most VFDs were designed with three-phase converter sections.

The converter is actually a three-phase full-wave rectifier which produces 325 volts dc, for a 240 volt VFD, or 650 volts dc, for a 480 volt VFD, and it stores this converted energy in a capacitor bank.

This, then, is the first section of a VFD.

The second section of a VFD, then, takes the energy which was converted by the first section, and inverts this energy back into ac, but this ac is not only three-phase ac, it is variable frequency ac as well.

The second section must, necessarily, be rated according to the load motor to be driven, which is always three-phase.

However, the first section must, necessarily, be rated according to the power source, and to which must be applied a conversion factor.

The conversion factor is 1.0 for a three-phase source.

However, the conversion factor is at least 1.732 for a single-phase source. Possibly higher than 1.732.

As 1.732 is not a round number, the conversion factor for a single-phase source is usually taken to be 2.0.

These facts, and factors, give rise to some rules-of-thumb, which usually state that a VFD must be derated by 50 percent when being driven by a single-phase source.

However, when blindly applied, this usually results in an over-specified inverter, and, sometimes, an under-specified converter.

Now, if the VFD is specifically designed to be supplied by either three- or single-phase power, then no derating is required.

Some VFDs, specifically those made by Polyspede, and possibly others, require no derating at all.

A possible down-side of this is the VFD may, necessarily, be housed in a frame which is larger than would otherwise be required.

A "7.5 HP frame" is common for a 5 HP-rated VFD which is capable of single- or three-phase input, without derating.

A "7.5 HP frame" is usually one size larger than a "5 HP frame".

The extra volume, then, is really designed to accommodate the larger converter section, although the inverter section may NOT be rated 7.5 HP, rather it may be rated only 5 HP, with a consequent reduction in cost, but not in volume.

With VFDs which were designed at the outset for single-phase input, there is no trade-off in volume nor in rating.

Rick,

The fuse rating on your lathe disconnect would be indicative not only of the horsepower of the machine but also on the voltage it was connected for.

A 5 HP motor connected for 240 volts shows a full load amp (FLA) rating of 15.2 amps. Your 15 amp protection would be a stretch even for this motor so I'm not sure what the lathe has.

The Polyspede drive is a little less than the Hitachi drive. The 5 HP Polyspede goes for around $649 while the 10 HP Hitachi goes for $680. I have used Hitachi drives before and they have real tech support so that is what I went with.

I power a 17" lathe and have acceleration and deceleration ramps set for a nice soft but quick start, and a fast stop of less than 3 seconds.

This stop is more than adequate and uses DC injection braking only, NO braking resistor.

The Hitachi unit has programming parameters that address over voltage trips on the buss from heavy overrunning loads such as the gear train/chuck of a large lathe.

Stuart

Thanks for the explanation on the de-rating, I was thinking that perhaps we were talking about the motor running on less power... silly me. I did not know that it was possible to run the three phase in units on single phase. Fortunately, no need for me.

Stuart, This lathe was wired for 220V and the owner (who purchased a Mori-Siki (SP) to replace it, is a friend. He told me that it would occasionally blow a fuse on acceleration when it had a big mass in the chuck.

I mis-read the web site, the drive is going to set me back over $500 (ouch). Seems the thing to do. I was half thinking of just using a phase converter since the lost power of the motor would not likely be a problem.

Thanks! Rick

Rick,

I am lost in all the posts.....again! If your lathe is a 5 HP three phase wired for 240 volts and you want to use a Hitachi frequency drive, you will need to purchase a 10 HP drive. These are sold at a very good price on eBay for $680 new. If you found one for $300 dollars it was either a real deal or the wrong deal.

You cannot power a 5 HP three phase electric motor from single phase power without doubling the inverter size. This of course does not hold true to a Polyspede unit which is oversize from the factory.

Stuart

Or you might consider a RPC.

If considering $$

Hee hee...

Dang, that's a whole lotta money... Is this going in a commercial business?

I found a 10HP three-phase motor for my 10EE... bought it from a local motor rebuild shop's 'dead stock' (customer had a special-shaft motor rebuilt, then went bankrupt, and never came to get the motor). I paid $25 for it... biggest investment was getting a buddy to help lift it out of my truck...

I found an Allen-Bradley 1336F 15hp 480v drive on the 'bay for $68.

I found a 15kva 240:480 transformer on Craigslist for $40... bought it for $30.

Had a bunch of appropriate contactors, pushbuttons, etc. lying around, so I hooked it all up for a test

Wired the transformer in backwards (240 in, stepping up to 480) to the VFD... and connected it to a 'test load' (blower on my grain bin) and it works great!

One of these days, I'll make an adapter to hook that 10hp wierd-shaft motor to the 10EE's backgear box (yeah, I know- it isn't necessary, but I'm doin' it anyway)... and have a nice, quiet shop afterwards.

atomarc said:

You cannot power a 5 HP three phase electric motor from single phase power without doubling the inverter size.

Click to expand...

Not true of the AC Tech drives, as I mentioned previously.

- Leigh

I've got a 10 HP Teco 7200M3 box with 220 V single phase input 440 V three phase output on the wall powering my machines just fine. The UK supplier does 15, 20 and (I think) 30 HP boxes too. Surely these can be got on the US market too. Don't Teco make boxes for Westinghouse?

Clive

Rick:

E-mail me at [email protected] and we can chat or if you are in Knoxville maybe you could see what I have done.

Howard

Rick,

I have a Fincor/ Boston Gear 10 hp drive that will be available in the next 2-3 weeks. The manual clearly rates the drive at 10 hp - 240v three phase and 5 hp single phase. I will be upgrading a machine to Vector Drive. If you are interested, PM me.

Paul