Newbie- 460 volt brushless AC Servo

[freecr]

Hello All,

I believe this is my first post here though I been a ghost on these boards for a while now. I may have wasted a hundred bucks ($135 with shipping) or more rather tied it up for awhile. I recently purchased a Parker MPP1422R (142 frame, 2 stack, R winding) servo off eBay. "R" winding means 460 volts. I have standard 115/230 residential power with 3-phase delta via phase perfect as well, but not 460. I had intended to attach it to a rotary table for a 4th axis. The short but fat and very powerful attributes I thought was going to be perfect. I am new to milling and to CNC. As far as servos, amps, motion control boards, encoders, etc goes I’m at best a novice. Just the servo types alone (brushed, brushless, AC, DC, feed back, control, etc) are confusing. I am currently converting a Fryer bed mill with a dead Anilam control to Mach 3. I have been helped thus far and hope to continue getting great help on that project though the forum on that site. I believe this problem/question is more suited for this site. Can I use 115 or 230 volt single phase, or 230 three phase delta, or a DC power supply to power this motor or to the amp to power this motor? It is a dedicated 460 volt not 230/460 servo. I haven't yet bought the amp yet. The mill will be using Mach 3 via a Galil DMC 4040 motion control board eventually. I was able to reuse the existing brushed DC servos for the X, Y, and Z axis’s with +/-10volt control for speed & direction. The alternate is to sell it on eBay and buy another. I’m in no great hurry so the loss would be reduced and maybe even turned for a profit but I really want to use it, if it’s possible and practical.

Thanks for any advice.

[mactec54]

freecr

You will need the servo drive that goes with the AC servo motor, & a step up Transformer to go from your PhasePerfect 208/230V 3 phase output to the 460V For the drive voltage

[Al_The_Man]

Originally Posted by freecr Hello All, I had intended to attach it to a rotary table for a 4th axis. The short but fat and very powerful attributes I thought was going to be perfect.

What size of rotary table were you going to put on a 4.5HP motor?
I did a retro-fit of an air bearing 5ft diameter rotary table on a Fanuc Mill, no where near 4.5hp?
In all probability it has a resolver for feedback so right there it would limit your options for drives.
Put it back on ebay!!
Al.

[freecr]

Thanks Al_The_Man & mactec54,

I think I'll just put it back on eBay. It seems the easiest. Al, the rotab is a 23" beast. I wanted a more powerful servo not so much to turn the table as to hold it while milling. This motor has a 2000 line encoder and I intended to also use different sized timing pulleys to get more resolution. At 10:1 that gives me about 1 minute of arc. The height of the motor would fit under the height of the table so if something stuck out it wouldn't have hit the motor as it rotated. I simply didn't know that it was a 460v motor. If you have any suggestions I’ll be most attentive and appreciative? BTW, I’m just a garage guy, not some big production business. Speed is not that critical and money is limited.

[Al_The_Man]

I notice one 36" Rotab listed, weighs 2000lbs, has 3/4hp tilt motor and 1/3hp rotation motor!!!.
Al.

[keebler303]

Current gets you torque, voltage gets you speed. You would have to know the voltage constant to know for sure but you can run the motor and drive from 230V power and it will work fine, it will just not be able to reach full speed. Good drives to look into are the Allan Bradley Ultra 3000. They are generally reasonably priced on ebay and occasionally you can get one for a couple hundred. They take step/dir inputs and use encoder feedback. The best match is probably the 2098-dsd-hv050 as it is rated for the 460V power if you ever get it, or sell it to someone who does. The 2098-dsd-030, -050, -100, -hv100 would all work pretty well too.

Matt

[freecr]

Al_The_Man,

I would be happy if it is bigger than needed. This is how I understand it please let me know where I’m wrong. Rotating the table is one thing, but holding it stationary (or rotating it) while something attached to it is milled is quite another. Sometimes I’ll be able to lock the table manually before cuts, sometimes not (positioning vs. moving during the cut). When servos are powered but not moving they hold the axis’s still. I believe this is called holding torque. This motor at 0 rpm has 100 lb-in (8 1/3 ft-lbs) holding torque. So the question now is whether 100lb-in is enough. I really don't know how big is big enough. Too much power is OK, too little not so much, within reason of course. I really don't know anything and am just guessing. I see the 23” diameter rotab as 11.5” of leverage against the motor if I’m milling near the edge. The mill’s spindle motor is 3HP so I’m not going to be running 6” face-mills on it either. I just spoke with a parker guy and he said the motor will work on 230v but at half the speed but torque should be the same. Power is speed and torque so that also is reduced. This is a home shop so speed really isn't much of an issue. This is why I think I need a powerful servo.

[Al_The_Man]

There is going to be some gearing of some kind on a rotary table.
Torque increases at the direct ratio of the reduction.
Maximum torque on a servo motor is typically maximum at zero rpm.
How much reduction is there on this table?
Al.

[freecr]

Matt,

Thanks for the reply. I did call Parker and talked to a tech and he said pretty much as you said. The only thing I have to be concerned with now is I can overheat the motor easier. Not that hard to avoid. Thank you for suggesting a drive as that was going to be the very next question if the motor is big enough.

[freecr]

Al,

Great question but I don’t have the pulleys yet. This project is in its infancy, I just (Monday) received the rotab after finally finding one that I liked for what I was willing to spend after 2 years of watching eBay. I may have missed a few opportunities by not checking more often but I don’t know. Then, after finding it, but before bidding on the rotab this motor caught my eye and I bought it just to find out after it arrived that it was a 460v motor. I’m still retrofitting the mill itself to Mach3. So now I have a motor that might be big enough and a rotab. I have nothing else yet, not even the cables or especially the drive. The drive is the next thing if this motor will work. Before I spend any more money I thought it would be better to ask questions first. I should have done that first. I may yet want/need to put a different encoder in it and/or use gearing via timing pulleys to get better resolution. I haven’t really thought it all out yet. I really need to bounce this off some people. Do you have suggestions for gearing? How high of resolution can I get? I assume encoders are spendy too, but that might be the best way. What ratio would you suggest? What’s the most for 8.33ft-lbs? Another approach would be the try it and see technique. I’m not rich but in the end it was just $135 and if it does get burned up then I know it was too small. Not my favorite approach $135 is $135 and it could prove way more costly than doing it right in the first place.

[Al_The_Man]

Originally Posted by freecr Al, Great question but I don’t have the pulleys yet.

I'm not talking pulleys, every rotary table I have come across includes gearing between the input drive shaft and the final rotation, whether handwheel or motor.
IOW, how many rotations of the input shaft for one rotation of the table?
Al.

[freecr]

Al,
Sorry, my fault. I have a SIP PD-5. I should have mentioned that from the start. It has a lever on the top that when turned fully disengages the table from the hand crank. Flick the table with your pinkie and it spins. It has a shaft that I intend to somehow attach a pulley to. I haven’t really looked at it yet. The hole from the top goes all the way through so that may come in handy as well as the outside of the shaft. The motor would be mounted on a base that I still have to make allowing the clearance for the pulleys and belt. From the bottom of the base to the top of the table is a little better than 7” while the motor is just shy of 7”. This is why I really like the dimensions of the motor. I’m planning to make it quick release so I can still use the manual crank, though a non-powered servo shouldn’t create that much resistance anyway. When engaged, the crank is one rotation per degree and via a vernier scale is accurate to one second of arc. Sorry for any confusion. It was so clear in my mind.