DIY rotary phase converter plans? 5HP.

[lgalla]

Diy,
Read this from the phase panel.
Here's how it all works:
You run a single phase 220 volt circuit from your panel to terminals 1 and 2 on the converter panel. You connect a three phase motor to terminals 3, 4, and 5. You connect your three phase machinery to terminals 6, 7, and 8. You include a ground wire in all three runs, and connect them to the included ground lug. That's it... you're done. My panel will start the three phase idler motor, and cause it to generate power to create the three phases. It will also balance the power to within a few volts of line voltage on all three phases. Your equipment will receive true three phase power, which will make it (and you) very happy!

I am not sure but think the idler motor is another motor you have to buy.
Larry

[diyengineer]

Diy,
Read this from the phase panel.
Here's how it all works:
You run a single phase 220 volt circuit from your panel to terminals 1 and 2 on the converter panel. You connect a three phase motor to terminals 3, 4, and 5. You connect your three phase machinery to terminals 6, 7, and 8. You include a ground wire in all three runs, and connect them to the included ground lug. That's it... you're done. My panel will start the three phase idler motor, and cause it to generate power to create the three phases. It will also balance the power to within a few volts of line voltage on all three phases. Your equipment will receive true three phase power, which will make it (and you) very happy!

I am not sure but think the idler motor is another motor you have to buy.
Larry

That sounds really nice and easy! Yes i want to use my 5HP motor as the idler motor. The ebay panel says it can start the idler automatically too. For now it should get me going.

In the future, a perfect phase will most likely be in my shop

[lgalla]

DIY please read this.
Build Your Own Phase Converter Plans - U.S. Phase Converter Standards Organization

[handlewanker]

Hi all, I went down this path a few years ago when I ran a Bridgeport mill on what I thought was a "converted phase rewire" on the actual mill motor....silly old fool!

I had the idea from what was being spoken of by a number of people that all you needed was a few capacitors and a start capacitor and the 3 ph mill motor would run on single phase.....I wish.

First of all the mill motor WOULD start and run....but after 15 minutes it got so hot I had to shut it down....hmmmmmm...rethink.....add a cooling fan to the motor....run time extended to 25 minutes by shutting the motor off as soon as the cut was finished.

This went on for about a year and I did many jobs I couldn't normally do without a mill, and the prospect of refitting another single phase motor in place of the 3 ph motor didn't appeal for one reason or another.

So browsing the 'net I came across the article that showed rotary converters and single to 3 ph conversion...the whole gubbins explained.

Apparently you need a pilot motor running in the single phase circuit to generate the other two phases to power the mill motor....it was a light at the end of the tunnel switched on.

I bought a 3hp 3ph motor for a few bucks on Ebay, and with a few capacitors etc assembled a "Rotary phase converter"....well almost.

After a bit of testing with various capacitor capacities, and you need a lot of combinations to get the variation right, I managed to get the voltages on the three outputs to more or less coincide.

The problem was, when a load was applied, any load, the voltages went up and down on the two generated legs.....hmmmmm, OK so I guestimated the average load capacity by trial and error, arranged the capacitos to get the voltages right and didn't allow the mill motor to run unloaded when not cutting.

This was OK, but the thought of harming the mill motor led me to go out and buy a dinkum 3ph convertor that adjusted the capacitors electronically as the load varied...all internally and automatically.....all for about $2,000.....spend the kids inheritence whatever....problem solved.

Taking the top cover off of the casing of the convertor revealed a 3 HP motor and more capacitors than you'd believe, circuit board to rival a computer etc....very neat.

It runs with a slightly audible humming noise and when the mills going You can't hear it at all.

There's a display on the front panel that shows you the load variation adjustment as you work.

I also bought a 3/4 HP capacity single to 3PH VFD to run a bandsaw I made, to eliminate the need to open it up to change belts for the speed control, as the original idea was for a 3/4HP single ph motor and 6 speed pulley arrangement.

Let it be known categorically....you CAN NOT SPEED CHANGE a single phase motor, due to the fact it reaches synchronous speed and likes to stay at that speed....slow it down under load and the start windings get switched in and you end up burning the start windings out.

All my single phase synchronous motors have been removed now, and those that are built in on items I bought are dedicated to that use, and are commutated brush motors, like a portable circular saw, a mitre saw, table router, 5 speed bench drill etc.

3 PH motors are so cheap they almost give them away, and the aquisition of a VFD makes speed change a dream......as long as you don't expect to go down in speed to the very low rpm's under load and expect the motor to not overheat.

I bought a 1HP 3 ph 3,000 rpm motor for $5 and it will be reduced primarily by fixed belt drive to 150 rpm and after that by VFD to the bandsaw drive wheel...the speed range only needs to go from 50 rpm on the drive wheel to 150rpm for cutting steel and wood.

You can mess with DIY or bought el cheapo phase converters but all you get in most is a converter that won't go with the load as it varies.

Most people don't realise that you can't use mechanical switching of capacitors under load without getting fireworks...LOL.
Ian.

[2006LJRubicon]

will the auto feeders and digital readout still work?

[handlewanker]

With a proper shop bought rotary phase converter I expect they would work and it would not affect them at all.

Even in a shop with 3 ph on line, the digital read out will be on one of the phases only, and the feeder motors most probably would be 3 phase, but only if'n the machine was designed for 3 ph, however you can still have single phase motors for feeders, (highly unlikely) with the main head motor on a mill etc running from 3 ph, depends on the manufacturers design.

Home built rotary phase converters are a very big compromise when it comes to balancing the voltages under varying loads, but shop bought ones (good ones, not el cheapo's) switch the capacitors in and out electronically as the load varies.

The big problem with rotary ph converters is that one leg is at mains potential, that is full voltage and amperage capability, whereas the other two phases are generated and WILL MOST DEFINATELY fluctuate as the load varies.

So if'n you have the digi read out on one of the generated legs you'll get fluctuations in the readings.....big time......and piling everything onto the live leg only makes things worse.

The answer is to buy once good, and never look back.....a poor man always pays twice.
Ian.