---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 10/04/24: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:17 AM - Rotary switch tank selection (Bob Verwey) 2. 05:49 AM - Re: O/Vprotection for internally regulated alternator (Finn Lassen) 3. 08:00 AM - Re: slightly off-topic, ATC '32 volt DC' fuse: Why not 120V? (user9253) 4. 07:18 PM - Re: O/Vprotection for internally regulated alternator (Charlie England) ________________________________ Message 1 _____________________________________ Time: 12:17:08 AM PST US From: Bob Verwey Subject: AeroElectric-List: Rotary switch tank selection I have three fuel tanks L - R - AUX I want to use one gauge to display the selected tank's quantity. On a similar installation I have seen, the one annoying characteristic of the setup is the fact that there is no damping of the needle movement when you change tanks, leading to violent swings when switching tanks. Is there a simple way of eliminating this with some basic components added to the switching circuit? ________________________________ Message 2 _____________________________________ Time: 05:49:46 AM PST US Subject: Re: AeroElectric-List: O/Vprotection for internally regulated alternator From: Finn Lassen I switched to that configuration in my efforts to solve my electrical glitches. You put the relay in series with the B+ lead. The relay coil is powered by a breaker and the crowbar is across the relay coil. The breaker can be as little as 1 Amp because the circuit now only powers the relay, instead of the field winding in the alternator. If the crowbar senses an over-voltage spike it triggers and shorts the relay coil voltage to ground (making the breaker pop) and the relay opens. I think Bob has reported as much as 160V output from a runaway alternator, so the relay contacts should probably be rated for that voltage as well as the amps the generator can normally deliver. Finn On 10/3/2024 11:51 PM, 1rv4 wrote: > > Hi > I seem to remember there was a crowbar type overvoltage protection device for internaly regulated alternators. It had a relay to disconnect the B-lead. Can anyone shed some light on this or maybe I had a bad dream? > Thanks > Chris > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=513852#513852 > > ________________________________ Message 3 _____________________________________ Time: 08:00:55 AM PST US Subject: AeroElectric-List: Re: slightly off-topic, ATC '32 volt DC' fuse: Why not 120V? From: "user9253" I looked at a couple of glass fuses in my parts drawer. They are rated at 250 volts. I speculate that the voltage rating has to do with the distance between the terminals. Glass fuses are an inch or more in length. The ATC and ATO fuse terminals are a fraction of that apart. If the distance between fuse terminals is not great enough, when the fuse blows, higher voltage can arc across the terminals. Lawyers might also have something to to with the voltage rating. :-) -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=513855#513855 ________________________________ Message 4 _____________________________________ Time: 07:18:59 PM PST US From: Charlie England Subject: Re: AeroElectric-List: O/Vprotection for internally regulated alternator Attached. Note that Bob later deleted references to using internally regulated alternators. But some versions of the Z figures using dynamo style alternators did include the relay & OV module depicted in the attached document. Also note that recent conversations on this list indicate that the SCR used in the OV module is no longer available. Bob is said to be working on an updated OV module. Virus-free.www.avast.com <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> On Thu, Oct 3, 2024 at 10:56=AFPM 1rv4 wrote: > > Hi > I seem to remember there was a crowbar type overvoltage protection device > for internaly regulated alternators. It had a relay to disconnect the > B-lead. Can anyone shed some light on this or maybe I had a bad dream? > Thanks > Chris > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=513852#513852 > > =========== =========== =========== =========== =========== > > ------------------------------------------------------------------------------------- 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.