On Saturday, July 31, 2010 12:30:08 pm Speaker To-Dirt did opine: > Hi Jon, my answers to your questions are below. > > > Message: 4 > > Date: Fri, 30 Jul 2010 12:13:31 -0500 > > From: Jon Elson <[email protected]> > > Subject: Re: [Emc-users] Another Newbie Question. > > To: "Enhanced Machine Controller (EMC)" > > <[email protected]> > > Message-ID: <[email protected]> > > Content-Type: text/plain; charset=ISO-8859-1; > > format=flowed > > > > > > The original Bridgeport drivers used a saturable reactor to > > limit motor > > current when not moving. At some speed the reactor > > was switched off to > > send full voltage to the motor drive. Are you > > controlling this? It is > > Jon, I am sending the phase steps (Gray Code) to the various axis > boards. To my, minimal, understanding it is the ACC board that controls > the reactors. Am I misunderstanding this? To be explicit, it was to my > understanding that the ACC board monitored each coils current and then > controlled the reactor based on the current it sensed. As soon as I'm > done with this reply, I'm going to go back into the service > manual....Gosh I hope I did not get this wrong. > > > an extra transistor on the driver board, so you need to > > drive 5 wires > > for each axis, 4 for the phases and one for the reactor > > control. If you > > are controlling the reactor transistor, you may be turning > > the reactor > > off at too low a speed, causing excessive current in the > > motor. > > Okay so just to be sure, it is to my understanding that the ACC board > does this. I still have that in the loop. I am replacing the the PDP-11 > stack with a PC and driving the two TTL phase step lines going into > each axis controller. > > >You > > > > probably are moving Z very slowly (a couple IPM max) when > > drilling, and > > if your reactor control is set to turn it off on any > > movement at all, > > that may be the problem. > > Just to help your thoughts out. The fuses blow during, yes, slow > moves, or after I turn on the spindle. But I think the spindle induced > blows were due to me using a faster blowing fuse than specified for. > With the ABC Bus Fuses 205V 15A I have not seen that happen. > > > If your transistors were going into thermal runaway, then > > it is very > > unlikely the drive would work after you replaced the fuse. > > While doing searches on this problem, I came up on several of your > other posts on the problem. Jon, you're quite the expert and Google > thinks highly of you on the subject. In those posts you mention that > BOSS <=5 machines like mine, don't like being run off of rotary phase > converters. As another data point my loaded voltages RMS Phase to Phase > are thus 209-209-189. Is my co-generated 189 too far out of balance to > cause this problem? I'm not sure my Z transformer is getting the > co-generated phase, but some of your past posts point in the direction > that troublesome axes usually are getting the low phase on home shops > like mine. > > Andrew
Two things come to mind Andrew. 1. that voltage is too low, that converter must be very old, made when the wall socket voltage std was 117 or lower, and I can remember 108. Today's 3 phase power is 127 volts from each leg to the neutral, which with the vector additions between phases will result in around 230 volts being measured phase to phase, so you are likely suffering from the effects of that lowered voltage. 2. The 10% unbalance will likely not be a huge problem. The 3 winding, common core choke would at least try to equalize that, but at the expense of even greater ohmic losses so the net effect of trying to treat it is probably a wash or even a net loss. Does this rotary inverter have any available adjustments that could serve to raise the exciter field current in the output armature? It may even be semi-fixed by some sort of move the wire to different taps method, read the docs on that puppy carefully. And just as important, can it be raised without magnetic saturation or overheating the rotating fields armature? Also, if its too small, it might not be getting to full speed, resulting in reduced frequency. I would call any out put frequency measurement below 57Hz as very good evidence that it is overloaded. Unless the driving motor can go into synchronous mode as it approaches full speed, it will never actually make a 60Hz output, more like 58.33 or so at its rated load. I am assuming 60Hz power, translate accordingly by that ratio if your power is 50Hz where you are. Anything here applicable? -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Children are natural mimics who act like their parents despite every effort to teach them good manners. ------------------------------------------------------------------------------ The Palm PDK Hot Apps Program offers developers who use the Plug-In Development Kit to bring their C/C++ apps to Palm for a share of $1 Million in cash or HP Products. Visit us here for more details: http://p.sf.net/sfu/dev2dev-palm _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
