---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 11/24/21: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 10:01 AM - Re: Re: Over Voltage Crowbar (Robert L. Nuckolls, III) 2. 10:41 AM - Re: Re: Over Voltage Crowbar (correction) (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 10:01:27 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Over Voltage Crowbar > >I think the existing selection provides a time delay of 10 to 11 >usec, depending on the voltage sensed. Yes, I think you are correct >that this might be a bit too "twitchy." Using the added cap as you >suggest is certainly an easy way to modify the behavior without >component replacement. Something that might be necessary for any >specific aplication. Legacy qualification for 14v avionics cites a requirement to stand off a 20v surge for 1 Second; 40v surge for 100 mS. Waaayyyy back when, we adjusted ov trip time constants to respond to a 14.2 to 20V step input in 50 plus or minus a few milliseconds. While 'useful' it was far faster than necessary and occasionally caused problems with nuisance tripping. If I were updating the OVM14, it would be processor based with a software timer that trips for any voltage event exceeding 15 volts by more than 500 mS. If the input drops below 16v before time-out, the timer resets and starts over. In any case, your trip response time target is defined in HUNDREDS of milliseconds. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 2 _____________________________________ Time: 10:41:41 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Over Voltage Crowbar (correction) If I were updating the OVM14, it would be processor based with a software timer that trips for any voltage event exceeding 15 volts by more than 500 mS. If the input drops below 15v before time-out, the timer resets and starts over. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.