Not sure why everyone is having such a hard time understanding the problem here, while unusual, for the red to go dead, it does happen. As was originally stated he thought lightning may have kicked it. So red is dead and white is light (on). So even though a relay (3 pole) sounds like the ticket I doubt you would get the contraption past the biomed electricians. Everything has to be at lwats UL approved and they won't like the thought of anything connected across the main buss and the gen buss. What about a battery bank on a charger on the red or white bank and the regular power supply on the other with diods for switching and isolation. That way you would isolate the main busses by more than a relay and the chance if backfeeding would be almost 0
Just my thoughts. Rob. Ks4ec Sent by Good Messaging (www.good.com) -----Original Message----- From: Ray Brown [mailto:[EMAIL PROTECTED] Sent: Sunday, July 13, 2008 10:30 PM Eastern Standard Time To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Switching a Repeater Betwen AC Sources Sorry, Ron, I disagree with the relay idea. If it's critical that the radio power supply be up all the time, then run it in the emergency circuits, which ARE active all the time. Our main ambulance radio and our maintenance repeater are on emergency power, as I specificied and coordinated the istallation of both of them myself. The only switching occurs when the power goes down, all receptacles (both white and red are now dead) then the generators fire up within 15 seconds, stabilize, and transfer the feed of the red receptacles from the outside utility to the generators. Power switches back automatically after utility power has been restored and stays up for at least 5 continuous minutes with no dropouts. Then the generators run on cool-down for at least 10 minutes. My CBET rating means I'm certified as a Biomedical Equipment Technician on 6 levels of the proper care and feeding of medical instrumentation, including power supplies. :-) And, Laryn, I re-read your initial statement. You had 2 repeaters AND a computer on the same circuit, and it tripped? Again, what all was on that circuit? If the printer was also on that same circuit, you need to get it off the red and on the white. But even 100 watt repeaters with linear supplies should only draw 4 amps each on full load, plus 4 for the PC and display. Something else is on the circuit. Shame you can't take pictures. Check with the hospital electrician and see what's up. Good luck! Ray Ron Wright <[EMAIL PROTECTED]> wrote: Laryn, Your thinking is good. A simple relay, 3 pole/double throw would do what you want and power the relay coil with your normal AC power. When it goes the relay drops out and connects the repeater to the RED emergency outlet. As someone else suggested switch all 3 wires of hot, neutral and safety ground just to make sure you are not connecting something that you should not. Some suggest runing the repeater on the RED emergency outlet and all else on the normal outlet. You need to check to see if this RED outlet is powered all the time and not just when the gen/emergency power is running. Since it goes to the generator it might not be. Easy to check by plugging a lamp under normal power conditions. The only problems I see is the sudden switching back and forth that might occur quickly serval times in a short period. Like turning on/off the repeater power supply rapidly, but don't think this would be an issue. 73, ron, n9ee/r >From: Laryn Lohman >Date: 2008/07/13 Sun PM 08:17:51 EDT >To: Repeater-Builder@yahoogroups.com >Subject: [Repeater-Builder] Switching a Repeater Betwen AC Sources > >We have two repeaters, plus an IRLP computer, on one emergency-fed >circuit at a hospital. There are normally no problems with this. >During a recent storm, the AC panel circuit breaker tripped, taking >everything down in the middle of our Skywarn net. > >There are two receptacles near our equipment. One is normal power, >the other is the red Critical Power receptacle. What problems would >anyone see if we would feed everything from the normal power circuit, >and if it would ever trip off, switch to the red receptacle. That >way, if lightning trips the normal circuit, we would instantly feed >our equipment from the red receptacle. > >This sounds so simple, and I'm inclined to build such a setup, but am >I missing something obvious that could cause problems? Any better ideas? > >Laryn K8TVZ > > Since 1974, the award-winning Alpert JFCS has helped families of all faiths throughout most of Palm Beach County, FL, via counseling, seniors services, residences for the disabled, mentoring children, support groups and a lot more. SOLUTIONS FOR LIVING www.JFCSonline.com Please take note of our new website and E-Mail Addresses. Please update your contacts ASAP. -------------------------------------------------------------------------------- NOTICE: This e-mail message and all attachments transmitted with it are intended solely for the use of the addressee and may contain legally privileged and confidential information. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, copying, or other use of this message or its attachments is strictly prohibited. If you have received this message in error, please notify the sender immediately by replying to this message and please delete it from your computer.
