Tips/Techniques 3 ph to single phase

[grease monkey]

so I posed a query online, how to convert 3phase power to single phase, or more to the point, how to run a 3 phase motor on single phase residential power, couple different ways,
1- the expensive route is to install 3 phase power into your home, (like my cousin did, WOW, what I price, and he had to disconnect is current single phase to his house and feed it from his new 3 phase service in his shop, guy has transformers all over the place), he's more than $24,000 into this, but runs a full CNC shop now from home
2- the the phase converter route come in 2 forms, a motor big enough for your load with the output shaft removed so you cant run loads on it and a control unit, or a fancy resistor load bank with its control board,
3- install a single phase motor, but if you're like me and my mill, the output shaft of my motor was something very specific to my mill and well, only available from manufacturer- if they make one, which sadly mine did not, so..... if your so inclined, like I've at least seen 1 guy on here do, he modified a motor to suit.
4- take your original motor to a rewind shop and have them rewind to a lesser voltage, my mill came 575v, I had them rewind the motor for 230v, still 3 phase, but a lesser voltage, and then install a vfd drive to use wizardry to produce the 3 phase, and voila! motor rewind cost me $1150 in London Ontario, vfd I found used for $150, done. manufacturer wanted $1900 for a 230v 3 phase motor and it was out of stock, no telling when they would get one. so I'm still money ahead

hope this helps!

 

[djberta]

Option 4 was likely the best way to go. Motor rewind and rebuild should be near new in performance for a long time. Vfd can be used simply as an inverter to go from 1to 3 phase and if you like give you some variable control.

 

[justin1]

I like the phase converter path as my milling machine is 5hp 550v so had to go down that path it was cheap compared to getting motor rewound or replace the motor. Im sure I could of jerry rigged something but it was less effort to build phase converter and the cost can be drastically reduced if your buy second hand. I think it was around 500$ all said and done.

Larger 3 phase motor come up pretty cheap in my area same as transformers they come up aswell.

I bought the caps new and the disconnect switch new aswell.

The beauty of phase converter is it can be as simple as using a belt to start a 3 phase motor being feed single phase to be used as an idler to start other motors that are 3 phase.

I use a 7.5hp motor fed into a 600v transformer to run my milling milling machine. It's cap start/balanced as I didn't like using a rope or belt to start as it's easy to pull the wrong way which makes your machine run backwards.

Lots of plans on PM forums to build them as complex or simple as you want. I had a buddy of mine who was electrician look over my wiring to make sure I did it correctly but I didn't find it too hard and there is also a few good video on YouTube that walk you threw how to set them up aswell.

Side note. It's usually not recommended to run CNC machines as the voltages between phases are usually not exactly the same and it messes with cnc hardware. But you can balance it out to be pretty close so older CNC machines probably won't notice. You can also buy CNC compatible rotary phase converters but they cost few dollars.

 

[Canadium]

I like the phase converter path as my milling machine is 5hp 550v so had to go down that path it was cheap compared to getting motor rewound or replace the motor. Im sure I could of jerry rigged something but it was less effort to build phase converter and the cost can be drastically reduced if your buy second hand. I think it was around 500$ all said and done.

Larger 3 phase motor come up pretty cheap in my area same as transformers they come up aswell.

I bought the caps new and the disconnect switch new aswell.

The beauty of phase converter is it can be as simple as using a belt to start a 3 phase motor being feed single phase to be used as an idler to start other motors that are 3 phase.

I use a 7.5hp motor fed into a 600v transformer to run my milling milling machine. It's cap start/balanced as I didn't like using a rope or belt to start as it's easy to pull the wrong way which makes your machine run backwards.

Lots of plans on PM forums to build them as complex or simple as you want. I had a buddy of mine who was electrician look over my wiring to make sure I did it correctly but I didn't find it too hard and there is also a few good video on YouTube that walk you threw how to set them up aswell.

Side note. It's usually not recommended to run CNC machines as the voltages between phases are usually not exactly the same and it messes with cnc hardware. But you can balance it out to be pretty close so older CNC machines probably won't notice. You can also buy CNC compatible rotary phase converters but they cost few dollars.

Wish I could see what you did in more detail. I've searched around the net quite a bit for ideas on how to do this but a plan/design never gelled.

 

[slow-poke]

Run a 3P motor from single phase power - cheapest/simplest solution just use a VFD

Get single phase power from three phase power, just connect the single phase load.

 

[Mcgyver]

If the challenge is 1P to 3P at higher voltages, there is also RPC with a 3P transformer afterward. Low cost and run as machine machines as you like. That's what I've done for 600V machines. Cost was was about $250 for a used transformer, but that was a few years ago. There is stepping up single phase then into VFD as inverter. I have a 430V machine running that way. Single coil transformers can do the trick and come up for small dollars.

The best way might be something like a Phase Perfect, but it's expensive. They come up for a few thousand used occasionally and give perfect 3P power. I'd have thought there'd more DIY versions of these, but can't recall seeing any.

Short of that, I like a VFD at a 220V machine. The drone of RPC and the required gymnastics to get to the other side of the shop to turn it on are getting old.

 

[justin1]

Good video about starting idler with motor

Good video about building cap start motor and more or less same design I went with.

Wish I could see what you did in more detail. I've searched around the net quite a bit for ideas on how to do this but a plan/design never gelled.

It's kinda a mess of wiring so would be hard to figure out just from pics. I'll see if I can find original wiring diagram I used but the 2nd video I posted covers it well.

 

[mbond]

To get single phase from 3 phase is trivial - just use one of the phases

to get 3 phase from single phase. Analog or digital conversion.

Analog is some variant on using a single phase motor to power a 3 phase generator. A purpose built rotary phase converter, or one of the home brew solutions

Digital options are diverse, but for a single machine VFDs are cost effective and simple. And allow other useful features