View Full Version : Rotary 3 Phase Convertors

05-26-2003, 08:37 AM
I have a Rotary Phase Convertor (made by an electrical repair shop) that came along with the CNC machine (10HP) I bought used. I contacted the convertor builder and he said not to run any other machines on the convertor when running the CNC as it was balanced for that one machine.
I have seen in supply catalogues that factory built CNC convertors appear to be built at what appears to be double the capacity that would be necessary for manual mills. I plan on getting a 2nd CNC (10 HP) and I am looking for any suggestions as to the brand, size, and any additional tips, before getting another phase convertor to run it.
Thank you.

06-07-2003, 07:24 AM
We love it.

06-08-2003, 08:55 AM
Thanks for the reply. Do you use the rotary or the digital. I've never heard of a digital rotary convertor before.

06-08-2003, 08:57 AM
Correction for above: not digital rotary but rather "digital 3 phase convertor"

06-10-2003, 10:45 AM
One other avenue that you might be interested in checking, instead of buying another Rotophase, is to get a variable frequency AC drive. Typically, if you buy a unit that has twice the desired motor load capacity, you can feed single phase in and get three phase out. Example: buy a 10 hp AC drive to run a 5 hp three phase motor.

If you think you might have use for variable speed on the motor you are planning to drive, this might be something to think about.

06-10-2003, 07:00 PM
Thanks for reminding me. I do have a variable frequency drive on my cnc lathe. I don't understand how it works but as you mention in you reply it seems to me, it must be something similar to the commercial roto phase double the capacity as I refered to in my first post. To run a 10 hp I should check into a 20 HP AC Drive. That would save a second motor from running, I'll see how much the initial outlay of cash is. I do remember some trial and error, experimenting having to be done when the lathe AC drive was first set up.

06-10-2003, 07:12 PM
If you are concerned with maintaining an accurate speed, I'd highly recommend a Baldor Vector drive. I have a vectorless drive on one mill and a vector drive on the other, and for low speed tapping, you can get far superior results with the vector drive, because it will hold a speed, and provide the needed torque, too. The vectorless drive becomes very gutless at a low rpm command, and you cannot even count on it being any certain speed.

Of course, you will need to add an encoder to your motor shaft for feedback to the vector drive.

$$$ :)

06-11-2003, 04:25 AM
$$$, Hows the saying go? It only costs a little more to go "1st class" :)

06-11-2003, 08:42 AM
Phase Perfect cost about twice what roto phase costs. But, you will never find cleaner three phase or better efficiency than with this unit. Ours is 20 HP.

06-11-2003, 11:34 AM
tahlinc (Jim),
Do you only run one machine with your 20 HP perfect phase? Or do you, or could you, run more than one cnc machine with your 20 HP unit just as long as the total doesn't exceed 20 HP.