On Monday, June 04, 2012 08:58:57 AM Dave did opine: > If you can, pull off the bus covers and attach some wires to the bus and > alligator clip to those wires with a good multimeter and leave it set on > Volts DC while you run the machine. Be careful though as cheap jumper > leads are probably not good for 600 volts. > But most machine tool wire ( the heavier stuff) is rated for 600 > volts. "Most" good DVM leads are rated for at least 600 volts. That > way perhaps you can glance at the meter when you hear the tone change. > > Dave Good idea, on the face of it, but I would highly recommend rigging an external resistive range multiplier in front of the meter as very few can withstand that sort of voltage for extended periods of time. The problem isn't generally one of heating of the internal resistors, but of exceeding the end to end voltage rating of the resistors, causing microscopic arcs from carbon grain to carbon grain, which degrades the resistance to the low side, sometimes to nearly a dead short for a 20 megohm resistor. A 20k ohms/volt multimeter would need 12 megohms as its buildout to make it read full scale on the 50 u-amp range when connected to 600 volts, but that, because of the applied voltage, should be a dozen 1 meg, 2 watt resistors in series in order to distribute the voltage stress across the individual 1 meg resistors and be stable over extended times. You are interested in the variation, not the absolute reading. I'd use 13 1 meg R's just so there was room to read a slight rise too.
. A multimeter, like an old Simpson 260, will gradually start reading high, but eventually will pin the needle and let all the magic smoke out. Don't ask me how I know. :) > On 6/4/2012 6:40 AM, John Thornton wrote: > > Yesterday I made some parts and had a giant fan on the drive to see if > > it is a cooling problem. After about an hour or so the drive tripped > > out. I forgot to mention that the only thing moving during these > > faults is the Z axis and it is moving up ie the most loaded > > direction. Of course I can make it trip out with S6000 M3 so it does > > point to the infeed unit. I checked the internal cooling fan on the > > drives and they all are running. After the fault I reset the drive > > and continued to finish the last 5 parts without a fault. When it is > > about to fault out on a rapid Z up move I can hear a change in the > > tone of the Z servo and it starts to grunt for lack of a better word > > to describe the sound. > > > > The 600vdc buss is well protected as well as all the parts of the > > drive system. By the time I could get it open on the bench any hot > > part would be cool. > > > > I'll check the AC ripple today when I make some parts. > > > > John > > > > On 6/3/2012 1:50 PM, Jon Elson wrote: > >> John Thornton wrote: > >>> Currently with the 10hp idler and the Samson lathe running as a > >>> second idler and the 611 in the BP 308 on I have the voltage > >>> balanced at 245 between all three phases give or take one volt. The > >>> VMC will make parts and run at 2k with full rapid speeds or ramp up > >>> with G code to 6k and run about an hour or so before the drive > >>> trips out. Turning off everything for a while and whatever caused > >>> the trip seems to mend itself. So now I'm thinking that there might > >>> be an actual problem in the infeed unit because once it starts to > >>> trip out if I reset the machine and start running again it trips > >>> out real fast. > >> > >> Ah HA! Something is getting hot, most likely. So, it takes an hour > >> to heat up? > >> That suggests something massive, or possibly with a poor heat sink. > >> It is dangerous to work around inside the machine with 600 V DC in > >> there. Can you borrow a thermal camera? otherwise, you'll need to > >> power down and wait for the caps to drain, and then feel for > >> anything getting hot. One other possibility is if it takes an hour > >> to heat up, a modest fan might keep everything cool enough to make > >> it run continuously. > >> > >> One other thought, you might have TWO different problems! One is in > >> the infeed module, the other might be something wrong with the > >> spindle servo drive. it may have a bad cooling fan or something. > >> > >>> Monitoring the generated phase voltage while running and during > >>> rapid moves of Z I see no more than one volt variation. So that > >>> seems pretty stiff to me. > >>> > >>> The spindle and axes are all Siemens AC servos. If I changed to a > >>> VFD then I would loose my tool changer which would suck. I'd be > >>> more inclined to buy another VMC that didn't have a Siemens > >>> Simodrive 611 than try and mod this one, then sell the Discovery > >>> 308 on flea bay. The sad part is I have more $ invested in BT30 > >>> tooling than I care to think about so that clouds the issue of > >>> getting rid of the 308 for another VMC. > >>> > >>> I plan on calling Siemens back to see if there is anything I might > >>> do to reduce the sensitivity of the drive. The one thing that > >>> sticks in the back of my mind is how crappy the wave form was when > >>> I removed the commutating reactor from the circuit... anyway a lot > >>> to wonder about. > >> > >> The waveform will be crappy due to the rectifiers connecting the cap > >> bank first to > >> this line, then to that one. There will be large current pulses. > >> > >> Have you measured the AC ripple of the DC bus? Put a DVM on AC and > >> see what numbers you get under loaded conditions. > >> > >> Jon > >> > >> Jon > >> > >> --------------------------------------------------------------------- > >> --------- 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 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) My web page: <http://coyoteden.dyndns-free.com:85/gene> This login session: $13.99 ------------------------------------------------------------------------------ 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
