# 3 phase converter help



## Michaeljp86 (Jan 6, 2013)

For my lathe I bought a static converter to run it on 220V single phase. Ive read that with a static converter you only get about 2/3 of the hp that the motor would make on 3 phase because it only adds the 3rd leg to get the motor spinning after that the motor is only on 2 legs.

I did some work at a machine shop that only had single phase power and he would start up a 3 phase machine to make 3 phase power. So to use lets say a lathe he would fire up a mill off the static converter and the motor would act as a generator on the 3rd leg. So on his lathe he would have power on all 3 legs all the time.

Ive been reading and watching youtube videos and this looks like how a rotary converter works, just a static converter starting a motor. So I was wondering, couldn't I find a 3phase motor and start it off the static converter and then have 3 power legs to the lathe? 

The reason I ask is my lathe seem to weak, I cant run it at higher speeds.


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## bvd1940 (Jan 6, 2013)

A 3 phase motor dont need 3 phase to start, just spin it up with a small 1 phase motor & go for it.
You can add capacitors and balance the lines.
There is a thread here on rotary phase converters there use and design, then Google diy rotary phase converter and you will be reading for a few days.)


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## Michaeljp86 (Jan 6, 2013)

bvd1940 said:


> A 3 phase motor dont need 3 phase to start, just spin it up with a small 1 phase motor & go for it.
> You can add capacitors and balance the lines.
> There is a thread here on rotary phase converters there use and design, then Google diy rotary phase converter and you will be reading for a few days.)



From what I was reading on DIY rotary phase converters it sounds like what I described above if I understand correctly. One video I watched the guy would just spin a 3phase motor to start it and then used it as a generator for the 3rd leg. My lathe just doesnt have enough power off the static converter.


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## Kennyd (Jan 6, 2013)

Get a VFD Michael, you will never regret it.  There are plenty of threads here to help...


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## Michaeljp86 (Jan 6, 2013)

Kennyd said:


> Get a VFD Michael, you will never regret it.  There are plenty of threads here to help...



isnt that just a speed control? you still wouldnt have power to all 3 legs of the motor


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## Kennyd (Jan 6, 2013)

Michaeljp86 said:


> isnt that just a speed control? you still wouldnt have power to all 3 legs of the motor



No sir, not at all.  A VFD takes 220v single phase (some can take 120v) in, and converts to 3 phase output.  It can do variable speed as well by varying the frequency.


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## Michaeljp86 (Jan 6, 2013)

Kennyd said:


> No sir, not at all.  A VFD takes 220v single phase (some can take 120v) in, and converts to 3 phase output.  It can do variable speed as well by varying the frequency.



I wired one up on a conveyor at a farm once, it had a digital display and was very expensive. Something wouldn't work right and some guy from the factory had to come out and hook his laptop up to it and do some adjusting.


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## bvd1940 (Jan 6, 2013)

Quick dirty way is get a 3 phase motor larger than the largest  hp motor you want to run and wire up to 220 1 phase get her spinning and put the power to the 3 phase motor use the 3 legs off the 3 phase motor to run your equipment.
If you have to much grumbling from the idler motor use caps to balance the three legs and it wont grumble.:thinking:


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## Kennyd (Jan 6, 2013)

Michaeljp86 said:


> I wired one up on a conveyor at a farm once, it had a digital display and was very expensive. Something wouldn't work right and some guy from the factory had to come out and hook his laptop up to it and do some adjusting.




Please search some Michael.

What horsepower is your lathe so I can help you find one.


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## Michaeljp86 (Jan 6, 2013)

Kennyd said:


> Please search some Michael.
> 
> What horsepower is your lathe so I can help you find one.



The tag on the motor says its 1.5hp


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## Kennyd (Jan 6, 2013)

Michaeljp86 said:


> The tag on the motor says its 1.5hp



Perfect.

Here is a name brand one, a Teco FM50: 
*http://www.factorymation.com/Products/FM50_230V/FM50-202-C.html*

Or a Chicom one from eBay:
*http://www.ebay.com/itm/1-5KW-2HP-VFD-AC-Variable-Frequency-Speed-Drive-/320701891116*


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## Michaeljp86 (Jan 6, 2013)

Kennyd said:


> Perfect.
> 
> Here is a name brand one, a Teco FM50:
> *http://www.factorymation.com/Products/FM50_230V/FM50-202-C.html*
> ...



Do these make true 3 phase power? Ive seen some nice welding equipment thats 3 phase but I heard they wont work right on a converter because its not true 3 phase.


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## fast freddie (Jan 6, 2013)

Michaeljp86 said:


> For my lathe I bought a static converter to run it on 220V single phase. Ive read that with a static converter you only get about 2/3 of the hp that the motor would make on 3 phase because it only adds the 3rd leg to get the motor spinning after that the motor is only on 2 legs.
> 
> I did some work at a machine shop that only had single phase power and he would start up a 3 phase machine to make 3 phase power. So to use lets say a lathe he would fire up a mill off the static converter and the motor would act as a generator on the 3rd leg. So on his lathe he would have power on all 3 legs all the time.
> 
> ...



the answer to your question is yes.  take a 3 phase motor and if you want it to SELF START use a static converter to start it and it will make 3 phase power for your lathe and other machines as well if you want.  that is the way i'm doing it.  use to spin it to get it going but got tired of that


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## Operator4100 (Jan 7, 2013)

Good Morning all, My brother and I did just that, we had a 5hp GE motor that turned 3450 RPM I think, bought a ststic phase converter to start it no caps for balance or the like and it works great, later on I got a metal box form lowes and made a distrubition panel and wired up all our machines to it, theres nothing special to it not rocket science, good luck to all, DW:think1:


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## swatson144 (Jan 7, 2013)

Guys I am not condoning anyone's actions, but please lets not let this deteriorate further. perhaps chalk it up as a bad day? Your cooperation in this matter is much appreciated.

Lets continue helping each other.

Steve


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## HMF (Jan 7, 2013)

*Reminder About Treatment of Others on Hobby-Machinist*

Reminder About Treatment of Others on Hobby-Machinist...				 When I started this forum, it was with the intention of maintaining an educational setting free of derogatory comments, flaming, personal attacks, snobbery and elitism. We all have a bad day once in a while. We all lose our tempers and say or type something we shouldn't have. That's normal human nature! However, should that happen to be "just your style" there are several other home machining forums that will suit you much better. I think of everyone here as friends. In fact, I hope that many of you will become real friends as a result of your interaction here, and many have. Beginner or expert, all posts and replies will be civil and without condemnation. It will be a forum where no member will be afraid to post or ask a question for fear of being called down. All machine owners are welcome. We sell no advertising, magazines, or other projects we want you to buy. All we do on here is discuss machining and related subjects in a setting of respectful co-existence.

This standard is ESPECIALLY expected of moderators. On behalf of the Hobby-Machinist, my sincere apologies. ​


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## arvidj (Jan 7, 2013)

Michaeljp86 said:


> Do these make true 3 phase power? Ive seen some nice welding equipment thats 3 phase but I heard they wont work right on a converter because its not true 3 phase.



My opinion ...

Do they make "true 3 phase power"? I think that depends on your definition of "True". I am not trying to be a smart a.. but just suggesting you need to consider what you are going to use it for and how "true" it needs to be.

Each phase the utility company provides is a 60Hz sinusoidal wave and the three phases are 120 degrees apart, so we will call that "true 3 phase power".

What comes into most homes in the US is known as 3-wire, single phase, midpoint neutral and is usually derived by putting a transformer across one of the three phases. 

First step in the search for an answer what a VFD actually does create is to understand how the VFD works. If you look at a block diagram the first block takes the AC input and converst it to DC. This is a relatively simple process and it is very easy to make it "input agnostic". Many of the VFD's can take either single phase or three phase as input the VFD can't tell the difference.

The next block in the diagram is the "generate the waveform" block. This is were modern electronics come into play. At the heart of it is a computer controlled "wave form generator" ... a digital synthesizer if you will ... and as such could generate just about any wave form(s) you could think of in as many phases you might like. In a VFD the wave form generator computer code has been specialized to focus on generating three sinusoidal waves 120 degrees apart just like what the power company delivers.

The wave form generator then feeds to the "power" stage ... the "D" part of the name ... where all of that DC that was created earlier is attached to the load ... in your case a motor ... with the power stage being driven by the wave form generator. Think of a component audio system where there are receivers, players, etc. feeding a pre-amp when then feeds the power amp which is connected to the speakers.

Depending on what the actual load is, the wave form generator and the associated power stage do a very good job of synthesizing the three phase power that the utility company would provide, to the point of the motor not actually knowing the difference.

As long as the output is under complete computer control there are a couple of other things the VFD can also do without breaking a sweat ... like vary the frequency of the output ... the "VF" part of the name ... from 0Hz to 120Hz which will vary speed of the motor and why you might feed three phase input into a VFD to then run a phase motor at various speeds ... like actually monitor the output to see how well the output of the power stage and the motor are getting along and make real time adjustments to the wave form to make sure the system is behaving as the user has said it is suppose to ... like modify the wave form to assist in starting ... like redirecting the output that comes back from the motor when the system is asked to stop causing the motor to stop rotating much more quickly than if left on its own ... like define the acceleration and deceleration characteristics of the motor to meet specific needs ... like drive the user nuts trying to set up as many as a hundred parameters if the user wants to really fine tune the darn thing ... but I digress.

I think that the power stage of the VFD has been fine tuned to work with the electrical characteristics of an electric motor. As such a welder may not present the correct type of load to work well. If it is a transformer based welder the combination might work as the load is an inductive load but you would not be able to use the variable frequency part of the VFD as the transformer is designed for a specific frequency and looses efficiency when other frequencies are applied. In short not a good VFD ROI. If it is an inverter based welder then I would think that it would already be able to take multiple kinds of inputs as it is doing the same thing the VFD is doing ... taking a plethora of inputs and converting it to DC ... the inverter part of the welder definition ... and then letting computers do their magic ... so again not a good ROI.

Just my opinion,
Arvid


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## Michaeljp86 (Jan 7, 2013)

arvidj said:


> My opinion ...
> 
> Do they make "true 3 phase power"? I think that depends on your definition of "True". I am not trying to be a smart a.. but just suggesting you need to consider what you are going to use it for and how "true" it needs to be.
> 
> ...



That was a lot of good info, my dad is a electrician and Ive worked with him many years. The phase converters we have worked on were either rotary or static and ran motors. 

My ideal setup would be to have 3 phase wired in the building where I add whatever I want instead of having to add some sort of converter to everything you buy. I could have that with a rotary converter but from what Im told by people trying to run things like welders they rotary converts don't work. I guess some welders will work but they wont work like they should and that's because the 3 legs are not balanced. 


Ive never really dealt with a VFD before other then the one me and my dad mounted for a speed control on the conveyer at a apple farm. The ones Kennyd posted are not as over priced as I figured they would be. 

So i guess I don't really have a option of making 3 phase power to run welders or plasma cutters. So I should either make a rotary converter or get one of these VFD gizmos.


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## Kennyd (Jan 7, 2013)

Michaeljp86 said:


> So i guess I don't really have a option of making 3 phase power to run welders or plasma cutters. So I should either make a rotary converter or get one of these VFD gizmos.



Yeah, running welders or other fancy electronic equipment is not what VFD's are for, or RPC's in my opinion.  The advantage of a VFD or a RPC (for motors) is they are very energy efficient, quiet, compact, and can add variable speed to the piece of equipment its powering.  They are very reasonably priced if the motor is under 3 horsepower, over 3HP they start to get pricey.


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## Michaeljp86 (Jan 7, 2013)

Kennyd said:


> Yeah, running welders or other fancy electronic equipment is not what VFD's are for, or RPC's in my opinion.  The advantage of a VFD or a RPC (for motors) is they are very energy efficient, quiet, compact, and can add variable speed to the piece of equipment its powering.  They are very reasonably priced if the motor is under 3 horsepower, over 3HP they start to get pricey.



Ill probably end up going that route. I can probably get $50 on ebay for my static converter. Since I probably wont end up with more machines for a while.


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## Tony Wells (Jan 7, 2013)

Since it has been mentioned, I'm not completely positive on the use of rotary converters and transformer type welders. I do know of an individual that ran a nice MIG on one, and I always worried about it, but he seemed to have no problem with it. I'd definitely consult a competent welding supply before I did it. And for an inverter style, Id think it inadvisable. But again, consult an expert, especially is the machine was new and under warranty.


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## GK1918 (Jan 15, 2013)

Since my mill purchase last week, been doing much reading and then gettin deeper in confusion.  So
It sounds like  I like FVD-  rotory- and I suppose static.  Yesterday out of the clear blue my old freind
(electrician) pops in with a heat/def. problem in the van.  What a stroke of luck.  Ill fix the van he will
fix the milling machine.  On the van I gotta take out radio, heat control panel cause the heater is
hot but some door is not opening thats vacuum problem.  By the time I got the radio out, he's got the
mill working something like 15min.  What I read about vfds is it has to be direct to the motors so there
goes my drum switch.  He put a new (out of the van) heavy duty phase o matic.  I read like all bad
things with them.  All I can say is, it starts right up, all motors work, quiet, I milled some T nuts, I cant
feel anything as said of that 2/3 hp thing.  I bought this really cause of power feeds and it has a 
rapid return with auto stops on both  X&Y.  Nice


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## Michaeljp86 (Jan 15, 2013)

GK1918 said:


> Since my mill purchase last week, been doing much reading and then gettin deeper in confusion.  So
> It sounds like  I like FVD-  rotory- and I suppose static.  Yesterday out of the clear blue my old freind
> (electrician) pops in with a heat/def. problem in the van.  What a stroke of luck.  Ill fix the van he will
> fix the milling machine.  On the van I gotta take out radio, heat control panel cause the heater is
> ...



So with a VFD I cant use the forward and reverse switch?


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## Kennyd (Jan 15, 2013)

Michaeljp86 said:


> So with a VFD I cant use the forward and reverse switch?



You can, it just needs to be rewired for low-voltage so it can connect to the VFD.  Lots of talk about that, GK1918 is mistaken.


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## Michaeljp86 (Jan 15, 2013)

Kennyd said:


> You can, it just needs to be rewired for low-voltage so it can connect to the VFD.  Lots of talk about that, GK1918 is mistaken.



What do you mean low voltage? I had to rewire the motor for 220V 3 phase. It was running on 440 when I bought it. 

That F&R switch is awful handy, Id hate to loose it.


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## Kennyd (Jan 15, 2013)

Michaeljp86 said:


> What do you mean low voltage? I had to rewire the motor for 220V 3 phase. It was running on 440 when I bought it.
> 
> That F&R switch is awful handy, Id hate to loose it.



The VFD connects DIRECTLY to the motor, NO switches are allowed switches in between.

Then, you control the machine from the keypad on the VFD or with remote switches (you can rewire your drum switch to be a remote switch).  We discussed this a lot HERE:* http://www.hobby-machinist.com/showthread.php/10543-TECO-VFD-help-please*


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## Kennyd (Jan 15, 2013)

Michaeljp86 said:


> What do you mean low voltage? I had to rewire the motor for 220V 3 phase. It was running on 440 when I bought it.
> 
> That F&R switch is awful handy, Id hate to loose it.



Another good thread: *http://www.hobby-machinist.com/showthread.php/3210-Wiring-reverse-off-forward-switch-to-vfd*

And another: *http://www.hobby-machinist.com/showthread.php/3504-Cutler-Hammer-9441H132A-Reversing-Switch *

Another: *http://www.hobby-machinist.com/showthread.php/8009-A-VFD-write-up-for-a-Webb-Mill*


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## Michaeljp86 (Jan 15, 2013)

Kennyd said:


> The VFD connects DIRECTLY to the motor, NO switches are allowed switches in between.
> 
> Then, you control the machine from the keypad on the VFD or with remote switches (you can rewire your drum switch to be a remote switch).  We discussed this a lot HERE:* http://www.hobby-machinist.com/showthread.php/10543-TECO-VFD-help-please*



That helped but also made me wonder if I should go with a VFD. Im worried about how it will hold up. We have a lot of temperature changes here and get lots of condensation. May be killer for those electronics. I keep the lathe sprayed with WD40 to keep away rust.


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## Rick Leslie (Jan 15, 2013)

I too was intimidated by the phase converter dilemma. I tried the static converter only on my mill and couldn't cut hot butter with it. I hit the salvage yard and found a good Baldor 5hp 3ph motor for $45. Wired it to the static to start and wired the 2 three phase motors together. My mill has never run better. The 5 hp acts as an idler motor (no load) and balances the three legs for the mill motor. If you already have a static converter, find a used 3 phase motor for the idler. The beauty of the rotary system is you only need one for any number of machines as long as the hp rating is higher than the highest machine you have. You'll need a VFD for each machine.


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## Michaeljp86 (Jan 15, 2013)

Rick Leslie said:


> I too was intimidated by the phase converter dilemma. I tried the static converter only on my mill and couldn't cut hot butter with it. I hit the salvage yard and found a good Baldor 5hp 3ph motor for $45. Wired it to the static to start and wired the 2 three phase motors together. My mill has never run better. The 5 hp acts as an idler motor (no load) and balances the three legs for the mill motor. If you already have a static converter, find a used 3 phase motor for the idler. The beauty of the rotary system is you only need one for any number of machines as long as the hp rating is higher than the highest machine you have. You'll need a VFD for each machine.



I may never end up with another 3phase machine so I was thinking I could probably get around $50 for my converter so Id have about $50 in VFD. But Im worried about it holding up with these moisture problems being my lathe isnt in a heated shop. Looking at it that way I may be better going the electric motor route like you did. Maybe next time Im at the scrap yard ill ask if they will sell motors they have.


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## arvidj (Jan 15, 2013)

Michaeljp86 said:


> So with a VFD I cant use the forward and reverse switch?



Maybe it is covered in the other links presented but I will try to provide a quick answer here.

Again, in my opinion ...

You can reverse the direction of a 3ph motor by simply switching the two wires that go to any one of the three windings. That is what the drum switch does.

Lets think about connecting a VFD but skip the drum switch, just wire it directly to the 3ph motor as directed. Turn the VFD on and the motor turns in *A *direction. If it is 'backwards' just physically switch the wires going from the VFD to the motor. Now everything is going in the right direction.

Now the beauty of the VFD ... from now on, to get reverse just tell the computer inside the VFD to 'electronically' switch the wires [actually it switches the relationship of the phases but the end result is the same] by pushing a button on the front panel of the VFD.

You will not lose the ability to run the motor in reverse, you would just not use the drum switch to control the direction. You would use the buttons on the front of the VFD. Note that the VFD doesn't care much about which direction they are going so most of the features available in 'forward' are also available in 'reverse' ... variable speed, etc.


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## fast freddie (Jan 16, 2013)

Michaeljp86 said:


> I may never end up with another 3phase machine so I was thinking I could probably get around $50 for my converter so Id have about $50 in VFD. But Im worried about it holding up with these moisture problems being my lathe isnt in a heated shop. Looking at it that way I may be better going the electric motor route like you did. Maybe next time Im at the scrap yard ill ask if they will sell motors they have.



from your first letter till now it sounds like you know what to do. if your worried about 50 dollars you might be in trouble


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## Michaeljp86 (Jan 16, 2013)

fast freddie said:


> from your first letter till now it sounds like you know what to do. if your worried about 50 dollars you might be in trouble



Just doing some math, a $50 VFD is a cheap route to go vs building a rotary converter. But a rotary converter will probably last me until I die. Im not sure how well electronics will hold up out there.


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## fast freddie (Jan 16, 2013)

Michaeljp86 said:


> Just doing some math, a $50 VFD is a cheap route to go vs building a rotary converter. But a rotary converter will probably last me until I die. Im not sure how well electronics will hold up out there.



how do you BUILD a rotary converter ? its just a 3 phase motor already built, all you have to do is wire it. you'll have to wire a vfd too


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## Kennyd (Jan 16, 2013)

arvidj said:


> So yes, you do not use the old drum switch but you do not lose the ability to run the motor in reverse.




That is a very mis-leading to those who are trying to figure all this out.  You can keep the drum switch to start, stop and reverse the motor, you just need to rewire it so it will now control the VFD rather than the high voltage side of the motor.


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## arvidj (Jan 16, 2013)

Kennyd said:


> That is a very mis-leading to those who are trying to figure all this out.  You can keep the drum switch to start, stop and reverse the motor, you just need to rewire it so it will now control the VFD rather than the high voltage side of the motor.



I agree that the sentence was not well formed. I have edited the post to "You will not lose the ability to run the motor in reverse, you would  just not use the drum switch to control the direction. You would use the  buttons on the front of the VFD."

I thought I would suggest the simple implementation first ... eliminate the drum switch completely and just use the buttons on the front of the VFD.

After that implementation was up and running one could move on to figuring out the configuration of the drum switch ... what contacts are SPST, DPDT, momentary, etc. ... and what setting and options would need to be defined on the VFD to allow the drum switch to be used with the "Intelligent Input Terminals" ... at least that is what Hitachi calls them ... and then wiring it all up.

Or am I missing some other configuration utilizing the drum switch that you envision?

Arvid


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## Michaeljp86 (Jan 16, 2013)

fast freddie said:


> how do you BUILD a rotary converter ? its just a 3 phase motor already built, all you have to do is wire it. you'll have to wire a vfd too



From what Im gathering a rotary converter just uses a 3phase motor and a static converter to start it. Once the motor is running it acts as a generator for the 3rd leg thats missing on single phase power. 



Kennyd said:


> That is a very mis-leading to those who are trying to figure all this out.  You can keep the drum switch to start, stop and reverse the motor, you just need to rewire it so it will now control the VFD rather than the high voltage side of the motor.





arvidj said:


> I agree that the sentence was not well formed. I have edited the post to "You will not lose the ability to run the motor in reverse, you would  just not use the drum switch to control the direction. You would use the  buttons on the front of the VFD."
> 
> I thought I would suggest the simple implementation first ... eliminate the drum switch completely and just use the buttons on the front of the VFD.
> 
> ...



I understand it now, you just need to tell the VFD what to do through a remote. I bought a millermatic 200 wire welder that didn't work. I got it home and tore it apart to find it caught on fire inside. It kinda worked the same way, used 24v dc for the remote to turn on the 115V wire spool motor and open the solenoid valve for the gas. Also to let welding current through.


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## Richard King (Jan 16, 2013)

My Dad  told me when he opened his shop in NE MPLS back in 1955, that area did not have 3 phase power and the power company showed him how to make a phase converter.  He said a few years later they brought in 3 phase to the area and he never hooked up, just used his home made phase converter.

Several years later at our cabin, we had a small shop and he made up another one.
Here is how he hooked it up.
He told me a simple formula for motor size is HP x 1 1/2:  If you have a 5 HP machine 3 /ph.  Buy a 7 1/2 HP 3 phase motor and 

 Connect wire numbers 4,5,6 together and wrap with tape.
Connect 1 phase power from your electrical switch to the 3/ph motor to wires 1 and 7 and your 3 phase machine, tape up,
Connect the other 1 phase wire from your electrical switch to the 3 / ph motor to wires 2 and 8 and another 3 phase to your machine. Tape up.
Connect the 3 /ph motor wires 3 and 9 to the last 3 phase to your machine.  

He had a pulley on the motor shaft and used an old lawn mower rope to spin the motor and flip on the single phase power at the same time and away it went.

I have seen guys connect a 110 volt motor on the 3 phase motor to start it spinning and after it started to spin they would shut off the 110 motor and it would spin free, I guess there are a few other ways to do it too.  But that's how you can hook it up.


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## joconnor (Mar 15, 2013)

Just a couple of points on RPConverters. They are not usually considered feasible for welders or plasma cutters because of the high current requirements of that type of equipment. I have also noticed that when my hoist has a full load hanging it sometimes don't want to start with the RPC running. When this happens I just start my lathe thus adding another motor/generator to the circuit and the hoist will start every time.


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