On Tuesday 08 May 2018 07:20:53 andy pugh wrote: > I have concluded that I have a problem with noise from my (shared by 4 > drives) servo power supply. > The STMBL drive controlling the 4th axis suffers from CRC errors with > the smart-serial control signals and shuts down. > > By the simple expedient of running it from a separate PSU this problem > seems to be eliminated. > (It ran fine all night yesterday). > > I don't see this as a good long-term solution, so I want to get rid of > the noise in the DC supply. This seems like a job for a choke, but the > cables have a braided shield.
The use of ferrite beads/sleeves only slows the "longitudinal" noise, and would effect every conductor passing thru them equally. But will have little to no effect for noises originating in the supply as these are generally out of phase, and the magnetic effect disappears by cancelation in the choke. I tried to use a coffee cup full of them in the lathe, but wound up building unregulated analog supplies, one for each motor. With nothing but a big toroid, a bridge, and lots of microfarads on the bridges output. Only then was I down to the drivers own switching noise. And that was brought under control by moving the motor cables shields from the - terminal of the driver, to the single point bolted ground. This is the same ground, but it gets rid of the noise on the - psu rail by bypassing that 8" of wire, so that all grounds are to that bolt. > > Should the shield pass through the choke, or should I strip the area > where the choke is installed? Is there a possible violation of the single point ground? Some cable shield grounded on both ends for instance? Or a possible failure of the supply's output capacitors? ESR from their aging comes to mind. And switchers do tend to abuse those caps. -- 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) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
