On Mon, Feb 1, 2016, at 05:31 PM, Gene Heskett wrote: > Greetings; > > Those of you reading the mail know I made a soft start circuit for the > spindle PSU. > > It basically consists of two SSR's in series, the first one being the > main switch that enables AC power to reach the transformer by way of a > 51 Ohm 200 watt inrush limiting resistor. And that after the filters > are charged, nominally 10 seconds, a second SSR is fired to short that > resistor, allowing the supply to make full output. Controlled by a > couple timers driven by the motion.machine_is_on signal. > > I had set the timers for a fairly speedy off, with the SSR across te > resistor being the first one turned off if I unclicked the 2nd button, > followed 5 seconds later by the first SSR being shut down. Sort of a > soft stop I guess. > > But today in playing with the pyvcp-pannel, I turned it off with the 2nd > button, and the 20 amp breaker I had put back in the service to replace > the ill eagle 30 amp dropped instantly. And repeated everytime I > stopped it with that button, 100% of the time. > > I cannot imagine where a momentary short might be. So I piddled with the > setp's in the hal file so the softstart SSR was left on for about 5 > seconds, but the main SSR was disabled in about .5 seconds, so that main > power was disabled before the soft-start SSR was disabled. > > Now its not tripping the breaker, which is cool. But the question is, > why did it trip 100% of the time before I did that? > > Other than an SSR surge internal breakdown to the case & sink, I cannot > come up with a valid reason for that behaviour.
These have metal baseplates? Connected to grounded sinks? You could rule out a breakdown to sink if you temporarily insulated the sinks from ground and went back to the old configuration. A single breaker trip with the sinks floating would tend to rule out that possibility. Is there ANY path from incoming line to neutral (or the other phase, if this is a 240V circuit) that doesn't go through the transformer? If the answer is no (it seems that way from your description), and the fault current isn't flowing thru the case of the SSR, then it must be flowing thru the transformer. The only way the transformer should draw that kind of current is for a cycle or two at startup, or if the core saturates due to a large DC component. Is it possible that one or both SSRs is only conducting on one half of the AC waveform? > > Is this the sort of behaviour anyone else has encountered while using > SSR's to control about 1.5 kw of AC power? > > 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> > > ------------------------------------------------------------------------------ > Site24x7 APM Insight: Get Deep Visibility into Application Performance > APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month > Monitor end-to-end web transactions and take corrective actions now > Troubleshoot faster and improve end-user experience. Signup Now! > http://pubads.g.doubleclick.net/gampad/clk?id=267308311&iu=/4140 > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users -- John Kasunich jmkasun...@fastmail.fm ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=267308311&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
