http://en.wikipedia.org/wiki/RC_circuit
from there: http://en.wikipedia.org/wiki/File:RC_Series_Filter_(with_V%26I_Labels).svg and the response: http://en.wikipedia.org/wiki/File:Series_RC_capacitor_voltage.svg Regards, Alex ----- Original Message ----- From: "John Thornton" <bjt...@gmail.com> To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> Sent: Wednesday, May 30, 2012 3:45 PM Subject: Re: [Emc-users] Commutating Reactor > Hi Dennis, > > I have a 2.5" diameter facing mill that I use and I don't notice any > difference when using that. My machine lights do not dim during > acceleration which I assume is a good thing. I'm in the same canoe as > you with 240v single phase my only option to work with. > > Before all the experiments I could get 0 to 2k with no problems and > would structure my programs around that or use the G4 pause and ramp up > to the rpm I wanted above 2k. > > I too modified my program using a pause between S values but only had to > do that going up in rpm. From 6k to 0 I've never had a fault. > > The resistor/capacitor would be a low cost experiment. How do you > calculate what the values are for the resistor and the cap? Did you put > the resistor in series with one of the control lines? Does the cap > connect to the upstream side or the downstream side of the resistor? > Maybe a stick drawing would help me understand... > > John > > On 5/30/2012 7:05 AM, Viesturs Lācis wrote: >> I am helping Dennis out and reposting his message to mailing list: >> ====================================================================== >> >> Hi All, >> >> I have been following this thread and want to put in my 2 cents. I >> had the same issue as John with my Bridgeport Interact 412-V. It's >> spindle is similar to John's: 7.5kW 60-6000RPM. My rotary phase >> converter is also similar to John's: 15HP TEFC with start and run >> caps; legs are balanced within a few volts phase-phase. >> >> When I set the spindle RPM to 6k and performed an M03, the mains would >> dip in voltage and the halogen light powered by the machine would get >> dimmer. The power meter for the spindle would peg at 180% of load as >> it was starting. The same occurred when stopping the spindle but the >> halogen machine light would get bright as the spindle dumped the load >> back into the grid. In each case I would get a voltage fault and for >> my machine this was a critical error. Rebooting every time I started >> or stopped the spindle just would not do. >> >> Also want to interject that a loaded spindle may be worse. John, can >> you get to 2500RPM consistently? Try putting a heavy tool in the >> spindle - like a 5-10 pound boring head or something. Will it trip >> out below 3k RPM? Is it spindle load related? >> >> The thing I noticed was the dimming and brightening of the machine >> light. This told me there was too much impedance between the VMC and >> the AC mains, i.e. the rotary phase converter. If bolted directly to >> 208V 3-phase this would not occur. Even though there is a 30A 3-pole >> breaker in the panel (with 3-phase), you are connected to a >> transformer that can supply 200A+ so the impedance is very low and >> voltages tend not to bounce around much. But I have single phase 240V >> in my garage so I had to make this work. >> >> I started experimenting and modifying my programs to work around the >> problem: step from 0-2k RPM, wait a bit, step from 2k to 4k RPM, wait >> a bit then up to 6k RPM. Same with stopping the spindle. My >> machine's memory is only 3.5k so this was cutting into my program >> storage and it was a pain. I dug through the machine schematics and >> found the spindle control signal was an analog 0-10V line. If I >> slowed the ramp up and ramp down command to the spindle controller it >> would perform the same function as gradually changing the RPM in code. >> I cut the 10V command line and inserted ~ 4.7k resistor in series. >> On the spindle controller side I put something like a 10uF capacitor >> to ground. This creates a low pass filter so fast transients like a >> 0-10V command to "get going" take a few seconds to actually make it to >> 6k RPM. The same with changing the voltage from 10V to 0 - it takes a >> few seconds for the command to reach it's final value. That did it!! >> Now my halogen machine light stays at a constant brightness through >> spindle acceleration and deceleration. >> >> John, I think I also read if jogging too fast with one axis your >> machine would trip. Don't remember what axis this was but on my >> machine the head is pretty heavy and the Z-axis servo should pull more >> current than the others if it does. I never had a jogging/voltage >> trip but you may want to look at rewiring the power circuit for the >> servo amplifiers to use the lower impedance 240V legs of your rotary >> phase converter. The servo amps may also be single phase within your >> machine but still on the machine side of the reactor and input >> transformer to make the machine work with universal voltage inputs. >> Does not mean it cannot be rewired. >> >> My fix was a few cents worth of parts to modify the CNC. Took less >> room than a 50kVA transformer and I still think the wild leg of the >> 15HP rotary phase converter will still move around even though there >> is a delta-wye transformer in between. That is a lot of money and >> effort to be experimenting with. >> >> >> Dennis >> >> ------------------------------------------------------------------------------ >> Live Security Virtual Conference >> Exclusive live event will cover all the ways today's security and >> threat landscape has changed and how IT managers can respond. Discussions >> will include endpoint security, mobile security and the latest in malware >> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
