Hello Jean-François! I am using Mesa 8i20 servo drives that do not have built-in power supply, it takes DC as power input so I am trying to figure out how to do that properly. It seems to me that only a pair of rectifier bridge and capacitor is not enough to keep fuses happy. I do not worry about discharging the capacitor - what I observed from initial testing with one 8i20, it seems to me that drive does slowly discharge it - voltage dropped to few volts within a minute or so. Peter, is that intended or was it just some kind of happy moment and I actually should worry about discharge circuit as well?
Viesturs trešd., 2024. g. 7. aug., plkst. 10:19 — lietotājs Jean-François Simon (<jfsimon1...@gmail.com>) rakstīja: > > Hi good morning, > > I never eared of a power rectifier directly connected to the line, > usually there will be like slow charge circuit through resistors, > often also a filter at input stage, like LCL with inductors. > > Based on the explanations, i can't figure the details, is it so you > design and built a custom circuit, or implemented existed > modified circuits ? > > Essentially, yes it depends on the power rating, and passed a > point, drives have both charge and discharge circuits, as you > can't feed up instantly, it would exceed some ratings. > > The parts damaged at fast charge i guess would be also the > diode bridge, some wire and connections, for capacitors i'm > not sure they would be at issue, though they can overheat > from the internal resistance. > > If i got it right, you are trying assemble modules (like a > rectifier bridge with other things, DC bus and inverters), > then we need to look at the module datasheet and ratings > to fogure out these things. > > It's quite wrong Caps remain charge, that should never happen, > all drives discharge the internal caps at standstill, something's > failed or missing. > > Regards > > Jean-François > > On 8/6/24 22:44, Viesturs Lācis wrote: > > Hello! > > > > Recently I have posted some questions about the retrofit that I am > > working on and now I have encountered an issue that I cannot figure > > out. > > The thing is that I am swapping original Yaskawa servo drives with > > Mesa 8i20. One of the things for that was 3phase rectifier bridge (it > > takes 230 VAC input and provides 340V output) and 4700 uF capacitor > > for smoothing the ripple. > > It took me some time and some patience from PCW to fix the config and > > in the end I got one 8i20 to move one joint in the machine. So my next > > step was adding 2 more 8i20 drives for remaining 2 joints. It ended up > > with a blast in one 8i20. So I replaced it as well as I had to replace > > rectifier bridge. But now my issue is that protection fuse is tripped > > as soon as I enable machine power. > > 1) only rectifier bridge connected - all good > > 2) rectifier bridge + capacitor - fuse tripped immediately > > Note that I have not yet connected DC bus to 8i20 drives. > > I checked capacitor with multimeter, it was showing 180V DC (and it > > did not decrease in that time that I was holding multemeters pins > > there). I am not sure if that is some residual charge from previous > > (which I doubt) or if that was some charge that was acquired before > > fuse was tripped, but this seems to me like a good capacitor. Is that > > correct? > > > > I do not understand why was everything fine in initial testing - I did > > turn machine on and off lots of times and capacitor was discharged > > (and recharged!!!) numerous times. I have swapped that fuse for > > identical unit from a machine that has yet to go through the retrofit > > process. And it is the same. > > > > So my question to electronics gurus - could capacitor be damaged or > > was it just a beginners luck that everything worked and do I need to > > introduce some inductor between rectifier bridge and capacitor to > > limit the startup current that charges capacitor? > > > > Viesturs > > > > > > _______________________________________________ > > 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 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
