Bob Swinney -- Phase converters

  Quoted Text Here  

Transitron eventually consolidated its manufacturing in New Mexico, and sold all of its plant facilities east of the Mississippi to Sparton Electronics.
The Florida engineers spun off their own transformer companies, most of which are still doing well.
LLoyd

On 2009-01-22, Lloyd E. Sponenburgh <lloydspinsidemindspring.com> wrote:
  Quoted Text Here  
    O.K. I see that they are still around -- but have no "history" link on their website.
  Quoted Text Here  
    Is any branch still doing semiconductor development? That is what they were doing when I was there.
    Thanks,         DoN.

  Quoted Text Here  
Dunno, Don. The only two guys I know who are still around here are 1) Running his own transformer plant, and 2) a county councilman.
LLoyd

    [ ... ]
  Quoted Text Here  
    Probably from me -- and this only applies that I am sure of for the BOSS-3 through BOSS-6 machines. BOSS-8 had moved to servo motors instead of steppers, and are probably easier to run from single phase (except for the spindle motor, of course.)
    Looking at the manual chapter which you posted a link to, this appears to be for the later ones, with a single power supply providing 128 VDC for all three axes from a single power supply -- thus it is probably running servo motors and servo amps (the "Motor Drive Module Assemblies"). This one will be easier to convert than the BOSS-[3-6] machines are.
    The BOSS-[3-6] machines have a *big* three-phase transformer, providing lower voltage AC to each axis motor electronics from a different phase.
    Each phase goes through a saturable reactor (mag-amp) and a bridge rectifier to a filter capacitor to provide power to the stepper driver for that axis. When stopped and stepping slowly, there is no current through the control winding of the mag-amp, so the voltage reaching the rectifier and filter capacitor is reduced to about 50V DC or less out of the filter. However, when stepping rapidly, a DC current is fed through the control winding, lowering the inductance greatly, and getting more of the AC through the bridge rectifier through to the filter capacitor (and the stepper drivers and motor). This produces an 80V power to the stepper motors to overcome the inductance of the stepper windings.
    The stepper motor machines have big cooling fins on each stepper motor to deal with the heat from the current. The servo motors are just plain cylinders with brush caps sticking out.
  Quoted Text Here  
    At least on mine, the contactors are mechanically interlocked. Actuate one (with a short pulse of AC) and the other drops out before the first closes.
    IIRC, the contactor coils run from 120 VAC (developed from a large step-down transformer which powers other things as well), and they are controlled by a 24 VCD coil relay plugged into an octal socket in the computer rack on the opposite side of the machine itself. (There are three boxes -- high power on the back, electronics on the right (as seen from the operator's position, and the interlocked reversing relay in another box on the side which also contains an outlet for a coolant pump, and another outlet for an operator's light.
    If you are running the spindle motor from a VFD, you want to get rid of the interlock reversing relay, and give low-voltage commands to the VFD (easily derived from the relay which switches the reversing contactor.
    I really should scan all of what I have for the older machines and send to you -- but too many of the pages are too large for me to scan reasonably, and I'm having problems getting the just acquired SGI computer (which comes with scanning software) to talk to the SCSI interfaced HP Color Scanjet 5c. (It is expecting a Scanjet IIc at best, I think.) The manual has gazillions of fold-out schematics too big for my scanner.
  Quoted Text Here  
    No reversing contactors should be between the VFD and the spindle motor. The VFD should receive commands to stop or to run forward or reverse -- at the 5V or 10V level.
  Quoted Text Here  
    It all depends on which version of the BOSS series he has. If it is BOSS-3 through BOSS-6, then things are more difficult. If it is a BOSS-8 or later, things are easier, and match your manuals. And your chapter 4 is a *lot* shorter than mine. :-)
    Enjoy,         DoN.

  Quoted Text Here  
single
  Quoted Text Here  
Nope. One AC supply runs off one 240V phase, a DC supply runs off a second 240V phase, and the motor runs off all three.
  Quoted Text Here  
...snip
True, but I still have to rewire the main harness to get both internal supplies on one phase.
  Quoted Text Here  
or in
  Quoted Text Here  
Unfortunately, it's also about four to eight times the cost for that VFD than what my RPC (locate OUTSIDE the shop, and thus "silent") would cost.
Oddly... even the folks who sell retro-fit kits for the R2E4, converting them entirely to new electronics, don't seem to want to mess with the spindle motor. They sell VFDs. They recommend an RPC for that machine. (?)
LLoyd

Lloyd E. Sponenburgh wrote:
  Quoted Text Here  
Yep, they are two seperate single phase transformers, they each connect to your 240V input. They were only connected to seperate phases on the three phase supply to better balance the load on the three phase and lower the amperage requirements.
  Quoted Text Here  
That's just a few wires, 30 min of work.
  Quoted Text Here  
The used VFDs I got from Iggy for $100ea would do it. New ones for a 2hp spindle are a couple hundred dollars.
  Quoted Text Here  
Don't know, haven't seen their retrofit packages.
From Iggy's docs, there is nothing special about the spindle motor. The speed control setup is funky and probably not worth messing with, but that in no way precludes the use of a VFD set for simple 60hz output to power the spindle motor.
I spent some 5+ years doing CNC service BTW, however, the machines I worked on were generally newer. How far are you from Dallas anyway?

  Quoted Text Here  
    [ ... ]
  Quoted Text Here  
    Assuming that it is not like the Bridgeport Series 1 BOSS-3 through BOSS-6. Those have a *big* three phase transformer in the back power box, with each phase separately feeding a saturable reactor and a bridge rectifier and filter capacitors. These three supplies power the three large stepper motors. The power needed by these steppers is sufficient tha they felt that they needed to spread it out over the three phases. The actual computer and lower power driver circuits are all derived from a single phase as you describe below.
    Later versions, starting with the BOSS-8 used servo motors, and were not nearly as power hungry, so they could be driven from single phase except for the spindle motor.
  Quoted Text Here  
    Unless it is an old stepper motor driven axis machine, in which case it may indeed be using the full three phases to power those electronics.
  Quoted Text Here  
    An imbalanced (voltage mode) RPC can fry the power transistors driving the stepper motors on this old design, so if you use a RPC, you need to take care to balance it beforehand -- at least with the BOSS-[3-6]).
    Enjoy,         DoN.

DoN. Nichols wrote:
  Quoted Text Here  
Iggy's docs indicate it is a servo driven system and that the power supplies are all single phase.

  Quoted Text Here  
you
BOSS-9, Don. Pete was right in all respects, except that the two internal supplies do run off two phases. But they certainly can be made to run off one. The BOSS-9 R2E4 is all servo driven, and not power-hungry, at all.
LLoyd

You can use a series of motors to get the capacity you need. If you want, you can do a sequenced start where one motor comes on line, use that one to start the second, the first two to start the third and so on. As long as the combined HP of the on line motors is significantly more than the newest one to come online, you can just run the new one as a pure 3 phase motor. Since you are starting them off the previous motors, you do not need to mechanically couple them. It does make sense to couple the first one or two to a single phase starting motor.
The downside of all this is the extra motors, extra switching, extra space, extra noise, extra power losses, and general hassle. Used 3 phase motors are cheap. If the windings are ok, the only thing that goes wrong is the bearings, cheap enough to replace.
Lloyd E. Sponenburgh wrote:
  Quoted Text Here  

On 2009-01-19, Lloyd E. Sponenburgh <lloydspinsidemindspring.com> wrote:
  Quoted Text Here  
Absolutely. No need to couple them mechanically.
  Quoted Text Here  
I have a phase converter with two idlers, which has a lot of benefits and no drawbacks. My idlers are 10 and 7.5 HP respectively. Using a lot of 1-3 HP motors would be messy, but not really electrically infeasible.
What were you quoted on a 7.5 HP motor?
Would you be interested in a new Reliance 10 HP motor?
I do not think that in a HSM context, you need a new motor for an idler. Even used motors have thousands of hours of service ahead of them, and phase converter does not load the bearings with anything besides the weight of the rotor.

in
  Quoted Text Here  
Might be, Iggy; How much? (and how to ship economically?) I love the old RE designs. They last forever. I have a 1968 RE 1HP TENV motor on a powder granulator that is still running as quiet and strong as it did new, and it's never had _anything_ done to it.
Are the 'new' ones as beefy as the 60's vintage motors? I re-painted the '68 one a while ago, and it weighed in at just under 90lb. A new one on another machine (of other manufacture; I think GE) weighed about 60.
Yes, I know I don't need 'new' motors, but I can get 3HP NEW Dayton motors for under $50, and with aggregate shipping, about $10 apiece to ship. I already have two (only one working as an RPC right now_), and they work fine with my 2HP spindle motor, even though the rotating mass on the new motors is MUCH lower than the older designs.
LLoyd

On 2009-01-19, Lloyd E. Sponenburgh <lloydspinsidemindspring.com> wrote:
  Quoted Text Here  
This is that sort of thing, in a cardboard crate (plywood bottom). TEFC motor. 10 HP.
$200 plus shipping, it is UPSable. Figure about 130 lbs weight.
This motor was never unbolted from plywood.
As I said, I think that if you look and find a used super cheap 10 HP motor, for say $40, you will be fine with it for your phase converter application, essentially forever. And no shipping to pay if you find locally, at some tired guy's warehouse, hidden in layers of dust and other crap. Given current economic environment, scrap price and general fear level, you should be able to do that.
But, if you want new, my offer will stand for a week or so.
  Quoted Text Here  
I am pretty sure that it is over 100 lbs, with the box but the box is not much.
  Quoted Text Here  
I would love to sell this motor to you, but in my honest opinion it is overkill for what you want. Find some garbage used motors and that will work just as well.
Just one more disclaimer, the motor I have is under a pile of stuff, and there is a very small chance that I either do not have it, or it is not 10 HP, but my memory is pretty good in this instance.

in
  Quoted Text Here  
because you're right -- if I really need a bigger unit, I can dig one up locally for a good price.
LLoyd

On Mon, 19 Jan 2009 14:16:56 -0600, Ignoramus16024
  Quoted Text Here  
That assertion certainly bespeaks authority.

  Quoted Text Here  
So, why do you think that they need to be coupled mechanically?

in
  Quoted Text Here  
Iggy, I don't think that was the issue he was addressing. ;)
LLoyd

On Tue, 20 Jan 2009 08:16:01 -0600, "Lloyd E. Sponenburgh"
  Quoted Text Here  
Right!

On Mon, 19 Jan 2009 09:13:26 -0600, "Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote:>Bob, I've got a theory question I might put in practice, if I've got
  Quoted Text Here  
As far as Im aware..and do this in my own HS...multiple motors simply add to the capacity.
My big 7.5hp Clausing 1500 didnt want to start on the 5hp RPC, but Id turn on the MasterMill and the HLVH, leave them running and the Clausing would fire right up.
Gunner

  Quoted Text Here  
Clausing
Sure... "no load" is the operative principle, though. Both the other machines are acting as idlers. If you loaded the first two machines, I'll bet the third wouldn't start.
LLoyd