At least one manufacturer (Tripp-Lite / Isobar) advertises that if your equipment is damaged from a power surge when powered thru their device they will repair or replace it for free. I use their surge suppressors for my computers, and have never had a problem, although they tend to make a horrible "bang!" on those occasions when they are killing a surge.
Also, I wrote up a small item for the Glowbugs list that concerns using Amperite thermal delay relays to automatically cut off power for 30 seconds or so when one of those one-second outages happens. Here is the gist of that post. You should be able to gleam sufficient information from the text to see what is happening, and how you could use the idea to your advantage. The original post was concerned about how to get around contact bounce with thermal delay relays, which open and close relatively slowly. A suitable delay relay is an Amperite 115NO30 (115 volt heater, normally open contacts, 30 second delay) which I believe is available from eBay or various surplus dealers, typical price: less than $20.00. The usual disclaimers apply. _________________________ The solution to the "contact chatter" issue is to use the thermal relay to activate a conventional relay that has the same coil voltage as the thermal relay heater. Use a set of contacts on the conventional relay, in parallel with the thermal relay's NO contacts to latch the conventional relay closed. This has several advantages. If wired correctly, this allows the thermal relay to be "de-powered" almost immediately after closure, thus effectively preventing heater burnout from prolonged activation, and the delay relay is aways ready for another cycle, instead of having to wait for it to cool down. The same SPDT contact set that uses its normally-open side to "latch" the conventional relay can, from the normally-closed side, control heater power for the thermal relay. If you use a DPDT conventional relay, then the set of contacts not used for latching and controlling the thermal relay heater can be used to switch the actual power load, avoiding the problem of burning the contacts of the expensive (and increasingly rare) thermal relay. The latching relay will drop out instantly on power off, so the cycle always starts fresh on each power on, no matter how long (or how short) the "off" period has been. I use this basic circuit in most of my power control systems, including multiple-outlet AC boxes, typically with a 30-second or so delay. In the event of a momentary power outage, the latching relay drops out at once and makes sure that sensitive items (hard disks, high-voltage power supplies, etc.) have completely spun-down or discharged before being re-energized. Has saved me any number of problems, and with a little more thought, allows remote control of power to whatever item(s) are being activated. _________ _________________________ - Jim, KL7CC JIM DAVIS wrote: > To the "Elecraft Crew", > > Many thanks for building into the K3 to sense when the AC power is not there > and "shut-off" > completely! > > I say this because earlier this morning here locally there was a PG&E power > outage. Initially the > juice went off and then just a few mil-secs the power tried to come back on, > which would mean > there'd be > a huge power surge to follow! I had my finger on the Astron-50m to switch the > rig off but I did'nt > have to really do that, in that the K3 sensed the power cut-off and "shut > down" immediately. > Everybody knows what "power-surges" can do to our solid-state rigs, and > eventhough most of our > power-distribution strips SUPPOSEDLY have protection against such occurrences > I've found that NOT > all > of them are cracked up to what they advertise!!! > > Many thanks for saving our "BABY!" > > Jim/nn6ee > S/N 2406 > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
