Phase converters, what is everyone using?

[zook]

Hey:

I am working on getting my Hurco CNC mill set up. My next step is getting a phase converter.

Is it worth it to buy a commercial one? Or should I buy/build a panel (you see them on ebay) and buy a used idler motor?

The mill is 3hp but i'd like a bigger converter in case i want to add on.

Thank you for your help.

Pat

[Al_The_Man]

You should check first if you really need 3 ph at this point as about the only thing that is probably 3 phase on a 3hp mill is the spindle.
It may take a VFD, if it does not already have one, and either case, a 3hp can be run off of 240 1ph.
Al.

[zook]

Al:

Doesn't running a 3ph motor on 1 ph burn it up?

Thanks.

Pat

[123CNC]

Running single, clarified.

What Al is referring to is running the 3 hp spindle off a vfd/vsd (inverter) that will accept single phase input and provide three phase output to the spindle. It is most likely that the spindle is the only thing requiring the three phase power. The rest of the controls are likely getting their single phase 220/110V circuit off a leg or two via a transformer to the required voltage level.

The sub 3hp range of VFD/VSDs are often very attractively priced in comparison to an RPC and give you added functionality to your mill. With options that include automated speed control.

[Al_The_Man]

This is a previous link of a Hurco retrofit, it looks like the Leeson VFD is running on 1ph.
http://www.cnczone.com/forums/showthread.php?p=464453
The VFD produces 3 ph variable frequency (speed), artificially from either a 3 phase source or single phase source.
Al.

[mc-motorsports]

If you just want a cheap rotary, build one! They are simple, and the same thing you will pay $500 for commercially, you can build for under $100 with a used idler.

BTW, I run 3 bridgeports and an engine lathe off of one 3hp converter that I built, works fine. I'm not saying you can start and stop all the machines at the same time, but I've had them all running at the same time, no problem. I run all three mills at the same time, daily.

Two 2hp mills, one 3hp mill and a 3hp engine lathe.

[zook]

Originally Posted by 123CNC Running single, clarified. What Al is referring to is running the 3 hp spindle off a vfd/vsd (inverter) that will accept single phase input and provide three phase output to the spindle. It is most likely that the spindle is the only thing requiring the three phase power. The rest of the controls are likely getting their single phase 220/110V circuit off a leg or two via a transformer to the required voltage level. The sub 3hp range of VFD/VSDs are often very attractively priced in comparison to an RPC and give you added functionality to your mill. With options that include automated speed control.

You're right, the only thing running on the 3ph is the spindle motor.

The VFD idea sounds great, which ones will work for this application?

Thank you for your help.

Patrick

[123CNC]

The Hitachi line (SJxxx) seems to be a popular choice. Automation Direct also seems to be a popular source/ retailer. For my Hurco I bought an el cheapo from an eBay retailer/ resaler and the drive came from an Illinois outfit, www.drivecon.com.

Another thing to keep in mind is that your spindle motor may not be very happy if you tend to run long periods at low speed via low frequency of the VFD, reduced airflow/ cooling of the spindle motor. I will keep my variable speed pulley system intact so that I can optimize between both, the VFD and vari-drive.

When looking for your VFD/VSD make sure the manufacturer states that it is designed to operate on single phase input or single and three phase rather than three phase only. If clearly stated, than a 3 hp accepting single phase will meet your basic requirement. Prices are good in this sub 3 hp range and many single phase input models exist.

If you have no luck or someone offers you a 5 hp 3 phase unit for free, most can be used with single phase input (but there is a general consensus, perhaps requirement on which two of the three input terminals you can use.) My point in mentioning it, is that a minimum size of 5 hp would be required to have the capacity to carry the higher amperage required on only 2 legs in order to drive your 3 hp motor (derated).

And yes mc-motorsports makes an excellent point of of the benefit of an RPC, making it a central utility to more than one device. Larger inverters can also be used in this manner, but they tend to be more pricey.

Good luck, I think you will be happy with the VFD route.

[Al_The_Man]

I prefer to look for the high end models off ebay, Mitsubishi, Telemecanique, Square D Altivar, etc.
Makes sure you get the programming unit if it is the detachable type.
Al.