OT: Lathe motor

OkiePC

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A buddy got a deal on an old lathe and wants to apply power...His shop has 240vac single phase.

I believe this old motor is a 2-speed 3 phase motor designed for 440vac but would like confirmation and advice on what to recommend. For starters, I told him he would do best with a low end VFD that can take single phase input, but I have never tried to put a 2 speed motor on a VFD and I am not sure how to proceed.

When I traced the motor wiring, some of the wires go to what looks like auxiliary contacts on the old contactors, and others seem to go to the main contacts. I didn't take thinks apart too far, but the contactors are different than others I have seen as well.

I think I located two sets of winding with my ohmmeter, but where they are landed had me befuddled. Anyhow if I do determine that there are two separate windings for two speed operation, how do I wire this thing to a VFD (if that is going to work at all)?

Thanks in advance!

LR motor plate.jpg LR Warner Swassey Contactors.jpg LR Warner Swassey No2.jpg
 
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Wire it for the highest speed, then use the VFD on it, and just use hard contacts to set the speed reference on the VFD. I would keep the RPM as close to possible to those rated RPM's as you don't want the motor running too slow to cool itself. As an aside, you will likely end up ditching those controls in the process.

Another viable option is going to be to get a phase converter and a transformer. Calling up the company will size them for you. They make some 98% efficient static phase converters that would work well for this.

Unfortunately, neither option is going to be super-cheap. They are both pretty much quick and dirty. I would move the new system to a cabinet and just run some wires to the lathe so that you can keep the equipment away from the shavings, oil and such.

The problem here is that motor. You can't just have it rewound because it is single phase, and a new motor would change the rating of the contactors and the control circuitry. No matter what you do, this is going to be a pita.
 
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I looks like a 40HP motor
I would replace the motor with a new 40HP 230V 3Ph vector duty motor
then install a 230V Vector VFD
you would have much better speed control then you will ever get any other way.
the VFD can be run on a 1 PH system without any problems
if you need help pm me
 
this is what I see from the name plate.


GE model CIN5702 motor

5/2.5 HP
the 40 is for 40degree c rise
Type K Code G Frame 284 3 phase
The volts has been scratched out and 440 has been stamped in
60 Hz
the FL Amps has been scratched out and 7.6 / ? has been stamped in.

in my opinion you have a 5 HP 440 volt 3 phase motor with a full load amp rating of 7.6 amps. it is not uncommon for a motor to be rebuilt and have the info stamped onto the name plate.

a 40 HP motor would be massive and I have never seen a lathe with that big of a motor even on a 40 ft bed with a 3 ft swing.

just my opinion.

james
 
I think Gary's misread the motor plate - 5HP at high speed & 2.5 HP at low speed . The 40 is the max delta temperature in deg C .

Ecogoo does a 9100-1T-00550-G-B drive rated 220v +-15% to 380v +- 15% at 5,5 kw . The price I saw was 284 $ .
 
I think Gary's misread the motor plate - 5HP at high speed & 2.5 HP at low speed . The 40 is the max delta temperature in deg C .

Ecogoo does a 9100-1T-00550-G-B drive rated 220v +-15% to 380v +- 15% at 5,5 kw . The price I saw was 284 $ .
5.5kW is too small. If you are going to feed a VFD with single phase, it must be AT LEAST twice the size of the motor. So you need a minimum 10HP VFD for a 5HP motor.


here's the thing though. If he only has 240V single phase and that motor is only capable of 440V 3 phase, you would ALSO need to buy a transformer to step up the 240V top 480V before feeding the VFD, then you need a disconnect, fuses etc. to protect the transformer, then again for the 480V side feeding the VFD, etc. etc. etc. Then on top of all that, feeding a 440V rated motor with a VFD should be done with added caution because the 440V nameplate defines it as too old to be designed for "inverter duty". So now you should add a dV/dt filter on the output of the VFD.



All in all he would probably be money ahead by just buying a new "inverter duty" 5HP 230V 3 phase motor and using a 10HP 230V VFD for it.
 
5.5kW is too small. If you are going to feed a VFD with single phase, it must be AT LEAST twice the size of the motor. So you need a minimum 10HP VFD for a 5HP motor.


here's the thing though. If he only has 240V single phase and that motor is only capable of 440V 3 phase, you would ALSO need to buy a transformer to step up the 240V top 480V before feeding the VFD, then you need a disconnect, fuses etc. to protect the transformer, then again for the 480V side feeding the VFD, etc. etc. etc. Then on top of all that, feeding a 440V rated motor with a VFD should be done with added caution because the 440V nameplate defines it as too old to be designed for "inverter duty". So now you should add a dV/dt filter on the output of the VFD.



All in all he would probably be money ahead by just buying a new "inverter duty" 5HP 230V 3 phase motor and using a 10HP 230V VFD for it.

I've ran into several customers that bought 3 phase equipment because it was more efficient. Sometimes it is because they didn't want to pay to get single phase powered equipment. Better that money goes to me I suppose :ROFLMAO:
 
Good info guys, thank you. Suppose this guy wants to risk running this motor with a VFD for as long as it can survive before replacing it with a vector duty motor...How would I wire it to the VFD?
 
That's not really a practical option because they will have to buy a transformer per jreaf, unless they want to be stuck with a transformer when that motor dies. I actually never thought about having to change the voltage fed to the VFD.

Else: trace those contactors out from line to the motor. That will tell you which set of windings to use.

Also found this page:
https://joliettech.com/information/...winding-easa-electrical-engineering-handbook/

No telling which it is, but you can trace wires and find out. As a general rule, this kinda stuff is a PITA.
 
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your friend has another issue and I can be wrong on this.

your picture shows 2 contactors and I am assuming that is the forward / reverse motor contactors.

the vfd will supply the power to the motor and can also do the forward/reverse.
I think , note I said think that the vfd will fault when you energize the vfd and no load is connected.
also, the vfd when powered and the motor is going forward may fault when you turn the motor off (lathe neutral) and then goto reverse.

for those with more drive experience, please reply as I may be wrong in what I said.
james
 
Good info guys, thank you. Suppose this guy wants to risk running this motor with a VFD for as long as it can survive before replacing it with a vector duty motor...How would I wire it to the VFD?

This is probably the reason your buddy got a good deal on it.

Part of everyone's job description is managing expectations.

If you're buddy thinks all there is to it, is to hook a cheap VFD up and it'll run a 440v motor on 240v single phase, then he has unrealistic expectations.

At some point your buddy needs to understand that 230v 3 phase 5HP inverter duty motors are readily available and not unreasonably expensive, as well as 10HP 230v drives.

Just my two cents.
 
5 hp is within the realm of single phase motors. I have doubts about dual speed, but if it’s dedicated for higher speed operation, a single phase motor might be worthwhile.
 
Jraef , the inverter model I gave is actually rated as 1 ph in at 220v and 380v out at 3ph and the output current is more than enough for a 5 hp motor . However the manifacturer is Chinese , and I have no experience with them . There are a couple of utube videos . Search for 1ph 220v to 3ph 380v inverter transformer .
 

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