Hi Gene, hope your doing well!
> IMO and unless the armature of that motor is some sort of a ferrite > compound, that temp s/n should not be a problem. Most motors can handle > temps too hot to lay your hand on them unless they are on their way out > in some sort of shorted windings failure mode. Most motor iron is grain > oriented silicon steel since about the end of WW-II, and that is not one > on its failure modes. > Indeed, from my experience with normal induction motors the temperature this spindle reached shouldn't be a problem. I didn't measure it with a thermometer but I felt it was somewhere in the 65ºC range. But since this is a high frequency spindle motor and materials are a little different I'm a little bit lost here. > The reason I mention ferrites is because there are ferrites that have a > "curie point" temp below 100C. But I've never heard of the ferrites > being used in motor armatures, just high performance transformer cores. > But that does bring up the possibility that the problem is actually the > vfd since its switching transformer is a prime candidate to use such a > ferrite compound. But that failure is in my experience, permanent > because if it passes the curie temp while energized, there is no > recovery short of returning the core to Arnold to run it thru their heat > treatment again to re-establish its magnetic properties. > Interesting, I didn't know they used materials with such a low curie point. > In both of those failures, encountered in H.P. brand power supplies at > the tv station, it was as if the core was replaced by air, and it > happened at such a low temp that the green paint on the core was not > discolored. > > I'm just guessing about your setup, my only high rpm spindle is the 24k > rev water cooled one I replaced with a better one on my 6040 mill, where > the water tank is about 4 gallons and a 3 day job making a hard maple > screw only gets the tank up to 36C in my air conditioned > garage/workshop. Its insulated, 6" walls full of cocoon, and a foot of > it on the ceiling, with a measly 5k btu window AC to cool the place. > > It sounds as if the motor is on its way out, but I'd not be totally > surprised to find the vfd was somehow being a problem. Measuring the > motor inductance, looking for not more than a 5% difference between the > three coils would be my first step. Next would be suitable light bulbs > on the vfd. I'd say look at its output with a scope, but that voltage > will probably destroy the scopes usual 10x probes, and high voltage 100x > probes are mail order far away. > > Whats your normal wall voltage? > I have 380 volts but I didn't had the chance to measure it today. I'll do it tomorrow. I wasn't worried about that because I assume the VFD would trigger an alarm in case of a voltage drop or missing phase. In fact all the servo motors are working ok. I just really hope this is a bearing problem, although I will have to import them anyway. El sáb, 4 mar 2023 a las 17:12, gene heskett (<ghesk...@shentel.net>) escribió: > On 3/4/23 13:53, Leonardo Marsaglia wrote: > > Hi guys. > > > > Sorry for the OT but I'm having a strange behavior with my spindle and > I'm > > a little worried. > > > > The problem I had today for the first time is the spindle was getting > > really hot and started to slip (you could hear the frequency from the > > inverter was on spot but the rotor sometimes wasn't even turning).After a > > few seconds of slipping the VFD triggered the over current alarm and the > > spindle was stopped. Once the the spindle cooled down it worked > perfectly. > > This never happened before but also I must clarify that today the ambient > > temperature reached 40⁰C and I'm sure that under that roof where the > router > > is placed there were 45⁰C so I suspect this has something to do with the > > problem. > > > > IMO and unless the armature of that motor is some sort of a ferrite > compound, that temp s/n should not be a problem. Most motors can handle > temps too hot to lay your hand on them unless they are on their way out > in some sort of shorted windings failure mode. Most motor iron is grain > oriented silicon steel since about the end of WW-II, and that is not one > on its failure modes. > > The reason I mention ferrites is because there are ferrites that have a > "curie point" temp below 100C. But I've never heard of the ferrites > being used in motor armatures, just high performance transformer cores. > But that does bring up the possibility that the problem is actually the > vfd since its switching transformer is a prime candidate to use such a > ferrite compound. But that failure is in my experience, permanent > because if it passes the curie temp while energized, there is no > recovery short of returning the core to Arnold to run it thru their heat > treatment again to re-establish its magnetic properties. > > In both of those failures, encountered in H.P. brand power supplies at > the tv station, it was as if the core was replaced by air, and it > happened at such a low temp that the green paint on the core was not > discolored. > > I'm just guessing about your setup, my only high rpm spindle is the 24k > rev water cooled one I replaced with a better one on my 6040 mill, where > the water tank is about 4 gallons and a 3 day job making a hard maple > screw only gets the tank up to 36C in my air conditioned > garage/workshop. Its insulated, 6" walls full of cocoon, and a foot of > it on the ceiling, with a measly 5k btu window AC to cool the place. > > It sounds as if the motor is on its way out, but I'd not be totally > surprised to find the vfd was somehow being a problem. Measuring the > motor inductance, looking for not more than a 5% difference between the > three coils would be my first step. Next would be suitable light bulbs > on the vfd. I'd say look at its output with a scope, but that voltage > will probably destroy the scopes usual 10x probes, and high voltage 100x > probes are mail order far away. > > Whats your normal wall voltage? > > > > The spindle is rated 11kw of max power output and is air cooled. It has a > > built in fan motor so it doesn't rely on spindle speed for cooling. It > > always gets warm (there are several labels on the spindle’s body for > > caution because of the heat) but nothing like today. > > > > Could this be normal because of the extremely hot days I'm having here? > > Should I think about changing bearings or even rewind the motor? I've > only > > had the over current alarms when the spindle was too hot. > > > > I will be really thankful if you can share your thoughts about this. > > > > Thanks for your help as always! > > > > Leonardo. > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > Cheers, Gene Heskett. > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author, 1940) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > Genes Web page <http://geneslinuxbox.net:6309/> > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
