# Converter recommendations for 2 speed 3hp 3-phase lathe motor



## keeena (Jan 18, 2020)

I picked up a lathe with a motor of questionable status. It's 3phase and I don't have a converter - so in the market for one. I've read through some great posts & threads, but figured I'd start a thread specific to the type of motor I have.

The motor is 3-phase, 220 volt TEFC. The lathe has high and low speed selector which will run the motor at 1800 or 900 RPM. Amperage is for high and low speeds is 11a and 9a, respectively. Connection is "YYY", class E, 60hz. The motor has 2 sets of 3 wires: one set for low speed and one set for high. This particular lathe lets you switch spindle from forward to reverse on the fly (can only do it 3x/minute per the manual)...no idea if that is pertinent. 

Given the motor specs: would a VFD be appropriate? What brands are recommended? 

IF the motor is toast, I'm not sure I would keep the lathe. But the VFD would eventually be re-purposed for a milling machine. Knowing this might factor into the recommendation as well.


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## mksj (Jan 19, 2020)

Not quite sure on the motor connections, I am only familiar with 2 sets of motor coils see below:




Sounds like a constant Hp 2 speed motor  running 4P/8P (1800/900).  I have had mixed results in running 2 speed motors with VFDs, but in general the constant Hp ones behave better. Most of the constant Hp 2 speed motors that I have used VFD's on have been mills which were 2P/4P and they were run on 4P to 120 Hz. Your setting is a bit different so you may need to try one or the other and see how the motor runs, so on the 8P setting I would run the VFD to 120 Hz, on the 4P setting to 60 Hz assuming the motor pulley ratio stays the same. I would start out on the 8P setting.

So the limitation that you will have is that the majority of 2.2kW VFDs have a maximum output current of 11.0A and many are less (or have other deratings factors), so you need to check that the VFD is rated for an 11A output in constant torque normal duty at the rated voltage. It is unlikely that you will be using the motor at full output, but you will probably need to dial down some of the VFD overload parameters if running on the 4P (11A) connection.
VFDs,  a few to consider that I am familiar with (there are many others):
Yaskawa, CIMR-VUBA0012FAA is rated for 12A CT output normal duty, 11A HD
Hitachi WJ200-022 SF is rated for 11A CT output
Teco Westinghouse A510-2003-C-U is rated for 11A CT output, the E510 does not have sufficient output, the L510 shouldn't be used for a lathe.

I have been using a number of Yaskawa VFD drives in some of my VFD builds, they work very well and have a very good reputation for reliability. On my lathe I use their 3 phase input  CIMR-VU2A0020FAA (20A output) with a DC choke and I derate it for single phase input, so it is good for around 12A output on single phase and 20A on 3 phase input (my motor is around 10A). My lathe control system is setup to run on either single or 3 phase input.  The down side on the Yaskawa VFDs is that there manuals are just OK and there are a ton of parameters, probably end up making changes to around 20 parameters. Hitachi there is a bit more information out there, manuals still are not great, Teco has very good manuals but relatively new series.

The V1000 would be my first choice and give you a lot of versatility should you change motors. I also use a similar VFD in some mills, but there are less expensive VFDs if you are just doing a simple install.








						Yaskawa, CIMR-VUBA0012FAA, 3HP, 1-Phase, 200-240V (Input), NEMA 1 Enclosure, Variable Frequency Drive
					

Yaskawa, CIMR-VUBA0012FAA, 3HP, 1-Phase, 200-240V (Input), NEMA 1 Enclosure, Variable Frequency Drive




					motorsandcontrol.com
				




You will have to use an external braking resistor for any of the above VFDs for use in a lathe. Typical braking resistor would be a 47 ohm 500W for a 2.2kW VFD 240V single phase input.


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## keeena (Jan 19, 2020)

Wish I could give this more than 1 thumbs up! @mksj - your posts were some of the ones I was referring to in other threads. I've seen Hitachi and Teco come up a lot in my searches. Thanks so much for the detail. A few Q's:

Given that the nameplate states YYY, does that mean I have the Dahlander config?

If I understand correctly: it sound like I would have to wire the VFD directly to the motor and wire the lathe's controls to the VFD in a manner to tell the VFD to send 60 or 120hz (if using the 4p/8p output config of the VFD)?

I had assumed/hoped that I would just use the VFD to provide 220v3-ph to the lathe's existing input terminals, set the VFD to 60hz and just use it like that; wouldn't use it for anyting other than getting 3phase out of it. Is that not possible? I attached a pic of the lathe's wiring diagram if it helps.


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## markba633csi (Jan 19, 2020)

I think you have a non-Dahlander motor; one of the first two drawings in post #2


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## keeena (Jan 19, 2020)

markba633csi said:


> I think you have a non-Dahlander motor; one of the first two drawings in post #2



That was my first guess but the motor label states "YYY"...?


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## mksj (Jan 19, 2020)

Probably because it is an 8P it may have some other arrangement of windings. A constant Hp 2 speed motor would have similar current draw at both speeds, yours is slightly different but is not the typical 3 Hp/1.5 Hp one would see for a 2 speed motor.

If you want a plug and play, get an RPC, connect the RS to the L1 and L2 poles, the wild leg is connected to T. Much easier install. A VFD needs to be a direct connect to the motor and low voltage controls used to operate the VFD commands. You can replace the contactors with AC relays to trigger the low voltage VFD inputs (strip out the 240VAC wiring to them), you need to replace the coolant pump if used.  You should not control the VFD with the spindle direction switch, the safe way is to use some relay interlock. If you have a foot brake you also need to have it dropout the VFD braking, issue a free run command) and also break the latching relay to drop out the run command.

It would be advisable to remove the motor pole changing switch, or you could keep it and just not use it. I have setup VFDs to run both sets of motor windings, it is complicated and at the end of the day not worth the complexity if you are going to do it correctly. If using the VFD you would setup the VFD to operate only one of the speed settings, I do not see any benefit of the added complexity of setting up the VFD to operate on both. You would need to setup the VFD setup with motor 1 and motor 2 parameter and use an input control to switch them, it gets complicated and not worth the effort. If plan to go the VFD route, as I indicated try one or the other setup and see which works best for you. I typically choose the higher pole configuration with a constant Hp motor.

I would advise just getting an RPC control box for around $200 and an inexpensive 5 Hp 1200 or 1750 RPM TENV idler motor and using the existing setup.


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## keeena (Jan 19, 2020)

I took a look at American Rotary for a canned solution: AR-5 (link), $460. This the right type of thing if I don't want to cobble together a solution? From what I understand: I wouldn't need a delta-wye transformer because my machine doesn't require neutral.

If i wanted to run any secondary systems on 120v single phase (light, coolant pump), would it make more sense to run those on a dedicated 120v circuit (completely independent of the 3ph) or spring for the transformer?

If I was building my own, is this (link) the type motor which would work as an idler? If CL ad is gone: it's a "Master" (made in Dayton, OH) 5 hp, 3-phase motor. 220/440v at 13/6.5 amps. Speed is 1725/1440 rpm on 60/50 Hz.

As I understand it, the RPC is always running between down time when using the lathe (e.g. when spindle is stopped to take measurements, swap chucks, etc...). This mean my electric meter will be spinning like a top any time the RPC is on?

Thanks so much for fielding my questions - its a big help!


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## MrWhoopee (Jan 19, 2020)

As a cheap way to get running and test things, you might try a static converter.









						HD 1 - 3 Hp Static Phase Converter Mill Drill Lathe Saw USA single - three SCM03  | eBay
					

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I was using one of these for my 2 hp 2-speed mill and 1 hp lathe. I was quite happy with it. I now have a 7.5 hp RPC and hate the constant whine, even though it's in the next room, and continuous power draw. I'm seriously thinking about going back to the static converter. There is a reduction of power with a static converter, but I never noticed it.


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## middle.road (Jan 19, 2020)

keeena said:


> I picked up a lathe with a motor of questionable status. (....clipped)
> 
> IF the motor is toast, _I'm not sure I would keep the lathe_. But the VFD would eventually be re-purposed for a milling machine. Knowing this might factor into the recommendation as well.


Well if it does come the that and it needs a home in a milder climate...


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## keeena (Jan 19, 2020)

@middle.road - You'll be first in line 

My understanding of static converters is that they are inefficient (2/3rds the power) and not good for long-term life of 3ph motors, so probably wouldn't want to go that route. But your concerns about RPC are probably why I had VFDs in my head as the best general solution for 3ph. So you have a point. And maybe it would be good to have one of these on hand as a fall back for testing stuff in the future...

Maybe I should buy a VFD + induction motor and be done with it. I suppose that's one benefit of just going that route...get the VFD, test it out...worst case plan on probably replacing motor anyway? I'll see what I get back for answers from my previous post on RPCs...


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## middle.road (Jan 19, 2020)

Oh, the joys of trying to run 3ph equipment in a home shop.
Someday I need to sit down and learn this stuff.
Thankfully we have some very knowledgeable folks around here always willing to help out.


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## mksj (Jan 19, 2020)

I would not use a static converter on a difficult load, and you may get some surface finish issues (this has been reported with surface grinders using static converters). If you want the simple approach, probably an RPC. Since it is a  bit more difficult load I would recommend a 7.5 Hp. A Y connection motor that does not connect to neutral would not need a transformer, it is what the motor sees for each phase as long as it is floating relative to neutral/ground. You can speak to the RPC manufactures and they can give you more details and recommendations. If you need 120 VAC, you would just use either L1 or L2 and neutral, not the manufactured leg. Also as I outlined previously, the transformer needs to be run off of L1 and L2, not the manufactured leg. You can purchase an RPC panel for under $200 if you can find a decent motor locally.

A VFD will be close to the cost of the RPC, and then you need an enclosure, power switch, fusing and rewire your lathe/control system. It all adds up, and if you just want phase conversion then an RPC is more cost effective. I have seem the American Rotary AMP cubes, they are very nice but more expensive. American rotary gives discounts, so if you watch certain Youtube videos they will have a discount code also Bar Z Bash 2019 there was a discount code. Others may have more info.


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## keeena (Jan 19, 2020)

mksj said:


> RPC...transformer needs to be run off of L1 and L2



Got it. I think the PO was trying to get this to run on a static phase converter, possibly undersized _(the SPC I saw was being used for a 1hp mill_). When I did some basic checks of the electrics I found that the fuse on one of the transformer's primary inputs was blown. If they hooked the wild leg to the transformer, would this explain blown fuse and ultimately why he couldn't get it to start? I've understood what you're saying about startup issues when a SPC and could have also been the PO's issue.

Given what I want to do: would a large enough static converter be OK for basic testing purposes? For now I just want to get things spinning so I can evaluate the rest of the lathe: headstock, geartrain, bearings, lubricating pump, etc... I'd only be out about $80 if I buy the SPC that MrWhoopee linked to. I wouldn't use the SPC for actually using the lathe.


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## mksj (Jan 20, 2020)

I am not well versed on the static converts, but it may work for testing purposes. There is a link below where one of the reviews said it did not work for his 3 Hp lathe, and yours might be a difficult start. My understanding is that some of these units might be used both as a static and an RPC by just adding a motor. You may need to tweak the capacitance. I would give these folks a call and see what they recommend or speak to a few of the other RPC distributors:





						WNY Supply & Phase Converter Store :: Home
					

Manufactures and sells phase converters online, large selection of rotary, static, panels, kits and parts available



					www.wnysupply.com
				











						HD 3 - 10 Hp Static Phase Converter Mill Drill Lathe USA MADE one to three SC10  | eBay
					

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## keeena (Jan 20, 2020)

markba633csi said:


> I think you have a non-Dahlander motor; one of the first two drawings in post #2



I just noticed the part manual for the front speed selector states "2 speed pole changing switch for Dahlander windings..."


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