3 Phase For Shop?

[Industrial Toys]

Are you a spy? Amazing. That stuff is on there?

As for my welder. I was at an auction, looked at the nameplate and it said 230, amoung other voltages, and stupid me assumed single phase. I didn't think there was 230 3 phase. I ran it on 600 off the converter. I could only get a ten hp idler motor at 600 so I kind of did things differently. There is a transformer between the extra capacitors and the idler motor running at 600.

 

[BHD]

one can make a rotor converter out of most any 3 phase motor that is larger than the motor you want to run,

the simplest, is to hook up the three phase motor two of the hots to the 230 volt single phase, (switched of course), and a small starter motor, to get the three phase rotating that is switch separately, tie in the three phase to the two hot single phase and the third off the motor, and you will have a rotary converter,

all the rotary converter is a short shaft three phase motor that is attached to a static converter, the static converter works as a starter for the motor, (rotary converter), and the motor acts as a rotary transformer, making up the third leg of the three phase, but the three phase motor will run on the single phase once it is started, (what a static converter does, a bank of capacitores shift the phase to make the third winding as a starter winding,

see post 98 Rotary Phase Converter Designs and Plans - Page 5

the thread also discussed the making your own static converter,

actually one can also do the same, with out the pony starter motor, with a slot and a pull rope, like an old gas engine,

this set up is a little crude but works,

 

[BHD]

second video of a similar set up,

 

[Stimw]

I ran a 50 Ton Scotchman Ironworker (5 hp) and a 15 X 54 Cincinnati Hydrashift Lathe (5hp) on a home made static converter for over 10 years. I retired and sold the lathe and have Ironworker for sale now.
The converter is only a relay, 2 capacitors and a resistor and cost me $45. to make.
The third leg is often called "phantom leg" and if you wire it into 120 V control circuit it won't work.
As it was explained to me, a 3 hp motor only has 2 hp on a static converter, 1/3 loss.

 

[grsthegreat]

I just installed a Phase Technologies 380 phase converter for a customer last week. Ill tell you what. Setting a 150 pound controller 8 feet in the air sucked. Couldnt get a forklift in to site. Took 3 of us to bolt it onto the unistrut. Nice piece of equipment. 200 amp single phase in and get 95 amps out. Very steady solid state unit. Very spendy though. But the guy is powering up a $65,000 mill, so he didnt mind spending 6 grand on the phase converter to protect his investment.

 

[TMGT]

I've had both a VFD and 2 different rotary phase converters. Personally I liked the adjustability of the vfd for thing like my vertical bandsaw and old South Bend lathe that only had 8 speeds.
When I bought my larger lathe (7.5hp) the cost of a compatable VFD was too much for me to justify. I was able to make my own rotary from a 10hp 3phase motor (free from my dad work) and a Phase Craft control panel off ebay (just found out the maker of the panels has now retired) with the starter.

Just hit a button and the converter starts, then use the machine, then hit the stop and it shuts down when I'm done. I get clean, well balanced output from this setup. Never really liked static converters, lower motor output and doesn't seem as smooth.

For anything 3hp and below with low startup load I do like the vfd.

 

[Whitbread]

I run my whole fabrication/machine shop on 2 rotary converters and one vfd. Both 3 phase idler motors were picked up from Craigslist or farm auctions for under $100. Control panels came from WNY Supply and I did all the hookups. Measuring voltage, all 3 legs are within 12v of each other. A 3hp motor runs my mill, belt sander, and bandsaw, a 20hp motor runs my Miller cp200 mig and thermal dynamics 152 plasma cutter. My lathe runs on a vfd because it only had 8 gears, so now I can do much finer speed control with the vfd.

Something that I haven't seen discussed about vfd's is the way they don't like switching. Case in point is my cincy mill; it has both a 3ph spindle motor and a 3ph power feed motor. On the side of the mill is a power switch that closes a relay to send juice up to the spindle motor switch and also starts the 3ph table feed motor. The electrical impulse that the vfd would read from closing the big relay on initial power up would trip it into an error condition. I eventually called Allen Bradley for tech support and thats when they basically told me a vfd is meant to run a motor directly only, no current drawing switching devices in between vfd and motor. So, I returned the vfd and built the rotary converter instead of hours of rewiring my mill internally and it works exactly as the factory intended now.

As for the vfd on the lathe, it only had a normal barrel switch that directly controlled the motor. It was easy to run the barrel switch to the vfd to let it command motor on/off and direction. Works like a champ!

 

[buickanddeere]

I ran a 50 Ton Scotchman Ironworker (5 hp) and a 15 X 54 Cincinnati Hydrashift Lathe (5hp) on a home made static converter for over 10 years. I retired and sold the lathe and have Ironworker for sale now.
The converter is only a relay, 2 capacitors and a resistor and cost me $45. to make.
The third leg is often called "phantom leg" and if you wire it into 120 V control circuit it won't work.
As it was explained to me, a 3 hp motor only has 2 hp on a static converter, 1/3 loss.

. A three phase motor operated on single phase only has 57.7% of it’s nameplate output .

 

[Industrial Toys]

I agree with not switching the output of a VFD. You can find them cheap enough, just use one for each motor.

 

[Larry Caldwell]

You guys are great. Trust a farmer to know how to set up a shop. I checked out the YouTube video on a rotary phase converter build at

Building a Phase Converter - Part 1 - YouTube

I looked for used 3 phase motors online, and a used 10 hp will cost about $250 delivered, maybe cheaper if I can find one locally. No motor is 100% efficient, but it would run at least a 8.5 hp load and pull a little over 30 amps single phase. At a guess, I could build the whole thing for $500. The video was great, but the wiring looks pretty puny. I would upsize the power lines to 8 gauge copper, but the capacitor connections would be fine with smaller wire.

Once again, thanks so much. I learned a lot, and it opened up some options I didn't know I had. If I get a 3 phase lathe, a VFD will be the way to go.