Greetings everybody; I have the soft start working, but have found that the capacitors are forming up to a very low leakage since they are operating at about half to 1 volt above their labeled voltage, which if it was turned on every day, the inrush probably would not trip a 15 amp breaker. Turned off at 5 ish because I needed to go see about a feedbag for us, and not turned on till nominally 1:30 in the afternoon of the next day, the normal operating voltage of 127 had only leaked down to about 115 volt. Since there's the equ of 2, 68,000 uF caps in series, that still represents a considerable shock hazard if I decide to do something that needs the + line touched.
So, here's my wild idea. Take another of those SSR's, ground the - control terminal, put a diode across the + to - terminals to absorb any - voltage, and charge a .22 uF cap connected to the + terminal and the drain of the SSR doing the original turn on thru that diode. The idea being that when that drain goes low, it will charge the .22, thru the diode, essentially maintaining that charge state. But when LCNC is stopped, that drain will go high (to 25 volts) as the supply is turned off, and as it goes high, so will the far end of that .22, carrying the + terminal on the third SSR far enough to trigger it. Nice idea, but these caps can also act as a battery because of their dielectric absorbtion, maintaining a small discharge current that when the bleeder is removed, potentially over the next hour bring the back of caps back up to as high as 20 volts. Because I don't know what the recovery characteristics of these SSR's are, the temptation is to feed the load r's normally grounded terminal, to ground thru a small tranny delivering 6.3 volts AC, which would seem to guarantee a shutoff at somewhere near the T=RC time where the R is 6 5k 10 watt resistors in parallel, and the C is the .068 Farad of the filter caps. With a startup delay 1.5 times that T, then I could be well assured that should I forget to do something, and turn it back on immediately, that time delay would prevent me from re-applying power before the third SSR has reset to the off state, which would leave the now hot bleeders still connected & using around 25 watts. Just from the CCS heat alone, thats not a great idea. What do you think? Is that a safe and workable idea? Or do I need to find a lower R than the 833.3333etc ohms that 6 of those 5K's in parallel represents? 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> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
