1994 VMC40

[cuyeyo]

Hi everyone,



Does anybody knows the problems I can run into if I run my machine with a Phase converter?

My machine is practically new, I had some guys rebuild it ( new motors, new inverter, I mean the works ). I know by what I've read so far in this web site that I will never be able to run it the same as if it was running on real three phase. So far I've noticed that if I run the spindle at 2499 RPM it'll be OK but if it goes to 2500 RPM the spindle will run counter clockwise but not at the 2500RPM. The other ploblem I found and this one really bothers me is that if I do a medium heavy rough cut on alum., when I come back to do a finish pass with a carbide e. mill sometimes it will not clean up on the X axis but if I run the finish pass again it'll clean it up. Are these problems related to be running with a phase converter?


Thanks for your comments.

[scadvice]

I think the spindle speed could be caused by alot of things but first off I would check and let us know the voltage on each leg going into the inverter. Also what kind of phase generator are you using and the voltage it is out putting to the transformer and what is coming out. I don't think the phase generator is the problem unless its the wrong size or incorretly wired.Are you just using MDI to turn the spindle on? If so, tell us what you are typing in. Are you saying that if you input S2499 M03 and on the next line type S2500 that the spindle reverses direction?
Is your machine a 15hp and have a four belt drive system? I recall on my 89 machine that the S command required a shift command at some speed (I don't recall what speed) an example would be 'S3500.2 to shift to high range. somebody else help me out here...
Lastly, are you new to programming? Do you have the manuals? Both issues could be related to programming errors, parameter issues, inverter issue, loose thrust bearings, lose gibs, offsets to the tool set wrong, and ect. We need a little more info.
Steve

[cuyeyo]

Hi Steve,

Yes, my machine is using not 4 but 6 belts, and I think is 15 hp. I already had some Fadal trained techs check the gives, motors, turkite, resolver on themotor, backlash I mean everything we could think of but it kept doing the same thing, it only got a little better when we lowered the feedrate so that's when they said it was probably caused by running the machine with a phase converter.

[scadvice]

If it is not mechanical (like a loose coupling or such)then IMO you may be better converting the standard 3 ph transformer for a single phase # 812 transformer. Like the phase generator you will lose about a third of your HP, but it is a factory option for the machine. Before that, a few last thoughts: Switch your power legs around and see if this corrects it. The generated leg may be dropping too much in voltage under startup load compared to the other legs and in its current location causing problems. Check the voltages coming off the phase generator to see that they are within 10% of each other (I think it is 10% range someone correct me if not).
Steve

[theisfarm]

What size is the rotary phase converter that you are running. I have a 97 vmc2216 with the 10,000 rpm spindle and I run 30hp rotary phase converter with no problems. I was told that your rpc needs to be twice the hp of the largest motor that you will be running.