On Tuesday 19 May 2020 14:01:23 Todd Zuercher wrote: > Are you sure your 40 amp SSR was what it claimed it was. I recall > someone on this list telling a story about how he opened up some > inexpensive SSRs to find woefully under spec-ed internal components > (like 1/4th the units rated capacity). > I have that in mind, these are from mpja.com, HOYMC brand. I bought a big bills worth of them several years back, this was the first failure, and I had zero trouble talking mpja into adding a freebie to todays order for 5 more. I am currently useing 2 to switch the vfd power from LCNC on the sheldon, and 2 to time the soft start of the spindle motor supply on the G0704, and by the time I'm done playing, I'll be switching the 704's XYZA supply too. Then TLM is next. I'm already using hard contact relays for all that on the 6040, but they will eventually weld shut I expect. I haven't really put it to work yet, heart attack got in the way and it took from late sept to mid January to get that all sorted.
> Todd Zuercher > P. Graham Dunn Inc. > 630 Henry Street > Dalton, Ohio 44618 > Phone: (330)828-2105ext. 2031 > > -----Original Message----- > From: Gene Heskett <ghesk...@shentel.net> > Sent: Tuesday, May 19, 2020 1:49 PM > To: Enhanced Machine Controller (EMC) > <emc-users@lists.sourceforge.net> Subject: SPAM: [Emc-users] > hypothetical, maybe not, switching psu question > > [EXTERNAL EMAIL] Be sure links are safe. > > Greetings all; > > Having destroyed one 40 amp SSR by turning on the switching psu;s for > the two running the X&y motors and the builtin supply of the even > bigger drive running the Z axis, already, I am now contemplating how > to do a soft start to limit the initial in-rush of charging up those 3 > power supplies. > > And doing it in a lower powered version of how I am doing the huge > analog supply that runs the spindle motor. > > There, I have two timers which are controlling two 40 amp SSR's with a > 50 ohm 200 watt resistor, so it starts charging that supply with its > thousands of u-f's by applying the power thru that big resistor, then > the 2nd SSR comes on applying it directly 3 seconds later. This has > worked flawlessly for about 4 years now. > > Now I have obtained two more used genuine crydom 40 amp 480 volt > SSR's, and am considering doing the same thing in essence, only with a > much smaller ohmage R to limit the in-rush this batch of switchers in > a similar manner. > > But switchers, I have heard, need that initial bump to get started > correctly. To that end I've also ordered a pair of 10 ohm 70 watt > resistors, which if need be can be paralleled for 5 ohms in series > with these supplies for the first 1/2 to 1 second. > > But I intend to use one of these in another analog supply, starting > the spindle psu in The Little Monster too, putting all its heavy power > under LCNC's control. But that is a different project. > > These switchers are, or s/b all fused to protect them in the event > they don't start. So I don't expect a start failure to do more than > blow the fuse. > > Has anyone else any experience with this, that can add gotcha's to > watch for in such a current limited startup? 10 ohms in series with > the power to protect the SSR's is the basic idea. 10 ohms would limit > at 12.5 amps of in-rush, which seems reasonable. > > Thanks all. > > 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) > If we desire respect for the law, we must first make the law > respectable. - Louis D. Brandeis > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > _______________________________________________ > 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 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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
