Phase converter facts?

[sharp-shooter]

First of all ,I'm new here and to cnc equipment. I recently purchased from a training school, a Bridgeport seriesI cnc R2E3. I believe it is a 1988 model in 2 hp.
I need a phase converter, but am confused with all the conflicting information I am getting. I know I need a rotary converter, but I keep hearing that because it is a cnc mill, it has to have a voltage stabilizer to keep the current balanced or bad things will happen.
I have been to Phase-a-matic's website, and filled out their sizing questionaire. Their recommendation was a 3 hp model with their voltage stabilizer. I don't doubt their expertise, but I don't want to get caught up in a bunch of hype and salesmanship. The fact is that I have an old home built converter that was used on another machine I had. It is built from a 5hp 3 phase motor, and was used on a Enco bench top mill. One of the capacitors went bad( I believe it was a start cap), so instead of replacing the capacitors, I replaced the motor on the mill with a single phase, it made more sense. So I have the makings of a phase convertor, providing that the motor is still in good running order, other than needing a capacitor or 2 or 3.
How important is it to have all the legs balanced, and how can I do it?
From what I've been reading on some of these forums, some commercial phase manufactures are getting big money for "cnc" compatible converters, that are not really special at all.

[tobyaxis]

Sharp-Shooter,

PM this guy he is the guru you need. Al_The_Man

BTW: Welcome to CNCZone

[lakeside]

Just went thru this a few weeks ago here some info and contact
Thank you for your telephone call today. Here is the information you
requested:

3HP All Purpose/CNC/Heavy Duty Rotary Phase Converter $ 345.00
Shipping via FedEx or UPS $ 75.00

This phase converter includes:
-CNC precision voltage balancing
-built in starter
-soft start
-custom made idler motor by Baldor
-24/7 customer and technical support
-24 month warranty
-simple installation
-quiet operation

More information is available at our website: www.americanrotary.com

L200-007NFU Hitachi VFD $ 215.00
or
SJ200-007NFU Hitachi VFD $ 276.00

Hitachi website is: www.hitachi.us/inverters

Please call or email me if you need any additional information.

Thanks again,

Jay
Yuergens
Application/Support Engineer
www.AmericanRotary.com
Toll-Free: 888-743-6832
phone: 262-268-7014
fax: 262-268-7015

[MaxHeadRoom]

I replaced the motor on the mill with a single phase, it made more sense. ????


How important is it to have all the legs balanced, and how can I do it?
From what I've been reading on some of these forums, some commercial phase manufactures are getting big money for "cnc" compatible converters, that are not really special at all.

Getting the balance as close as possible is a good idea, however the important thing is to ensure the 120 or 240v control is fed from the two main 240vac legs, and not the artificial phase leg.
Al.

[sharp-shooter]

Thanks lakeside, that was good info....

[wisp]

I bought a 15HP rotary converter from American Rotary as well. I am very happy with it. It is much quieter than my old 7.5HP converter from DES-CO.

The soft start is also nice, my old converter would always make a loud GRRRRRT sound as the motor got up to speed.

[sharp-shooter]

Well, I checked out the motor windings and they seem to be fine, so I got some new capacitors and will test the legs for balance once I get this thing to some juice. The only thing that bothers me is that the last time I run this converter, it seemed awful loud. It sounded like a dry bearing, but maybe it is because this motor is a flange mount vertical shaft. If it doesn't work out, I'm going straight to American Rotary for a new one and eliminate the headaches.

[sharp-shooter]

Well, I purchased the phase converter from American rotary and now I'm into another problem.
I got everything hooked up and tryed to power up the mill only to find out that it was wired for 208 instead of 240. One of the transformers is a dedicated 208 v, the other 2 are convertable 208,230,460. The only reasonable solution was to run it on 208, so I purchased a buck boost transformer to convert to 208. The problem is I still has 2 legs that are higher.
I am currently getting T1-T2=209 T1-T3=230 T2-T3=246v. The former owners told me that the phases must be within 2%.
The voltage is good going to the controller, now is doesn't have the quirks it had before, but the spindle will not start up because of an overvoltage.
The question is...what can I do to stabilize the voltage on the high legs?

[sdeering]

Not sure how they balance their converters. If they do it with caps. it looks like you have too much cap between the made leg and 1 and 2 legs. Adding caps between the made line and 1or 2 will increase the made leg voltage.
Stephen