---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 12/29/18: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 10:08 AM - Re: Fuse-able link (John Morgensen) 2. 11:33 AM - Re: Fuse-able link (Charlie England) 3. 07:03 PM - Re: Fuse-able link (user9253) ________________________________ Message 1 _____________________________________ Time: 10:08:08 AM PST US Subject: Re: AeroElectric-List: Fuse-able link From: John Morgensen Bob, I sent you the old parts minus the "sleeve" and I fabricated a new fuse-link that worked for about 2 flight hours with a new Plane Power 60amp alternator. It failed and when I pulled on the wire, it separated in the middle of the fuse link 22ga. A picture is attached. The old Plane Power Alternator was retained as a working spare. I don't know what to do next. It is not popping the 5amp circuit breaker but it is "frying" the 22ga wire. 600 hours on the plane. Originally, a PC680 battery replaced with an EarthX900 two years ago. Plane Power 60amp internally regulated with built in crowbar. Z-13/8 architecture and the wire that is failing is from the "Main Power Distribution Bus" bolt to pin 5 on the S700-2-10 switch. At this point, I don't understand what is purpose the fuse-link and why it has started failing. Thanks for any help, John Morgensen On 12/20/2018 2:14 PM, Robert L. Nuckolls, III wrote: > At 01:23 PM 12/20/2018, you wrote: >> >> >> Two years ago I had an over-voltage event and the crowbar protection >> behaved as expected. It popped the 5amp breaker. I had the alternator >> (Plane Power 60amp internal) repaired and it has behaved normally >> since then. The alternator stopped working this Sunday. The crimp had >> failed on the 18ga to 22ga fuse-link. Closer inspection revealed that >> the insulation under the heat shield on the fuse-link was almost >> completely gone. >> >> Questions: >> >> 1. Should I have inspected the fuse-link after the over-voltage >> incident before putting the plane back in service? >> >> 2. Is it acceptable to solder the joint between the 18ga and the 22ga >> or is a crimp connector required? > > I would really like to have that fusible link > assembly. Can you cut it out and fabricate > a new one? > > When you say "gone" . . . is it melted, charred, > evaporated? Was it Tefzel wire? > > That link normally carries 3A or less. I've > demonstrated that 22AWG Tefzel will carry > 20A indefinitely in the open air. > > Some combination of factors stacked up to > cause this particular link to suffer > damage. A good place to start is careful > examination of the link. > > > Bob . . . > ________________________________ Message 2 _____________________________________ Time: 11:33:32 AM PST US Subject: Re: AeroElectric-List: Fuse-able link From: Charlie England On 12/29/2018 12:06 PM, John Morgensen wrote: > > Bob, > > I sent you the old parts minus the "sleeve" and I fabricated a new > fuse-link that worked for about 2 flight hours with a new Plane Power > 60amp alternator. It failed and when I pulled on the wire, it > separated in the middle of the fuse link 22ga. A picture is attached. > > The old Plane Power Alternator was retained as a working spare. > > I don't know what to do next. It is not popping the 5amp circuit > breaker but it is "frying" the 22ga wire. > > 600 hours on the plane. Originally, a PC680 battery replaced with an > EarthX900 two years ago. Plane Power 60amp internally regulated with > built in crowbar. > > Z-13/8 architecture and the wire that is failing is from the "Main > Power Distribution Bus" bolt to pin 5 on the S700-2-10 switch. > > At this point, I don't understand what is purpose the fuse-link and > why it has started failing. > > Thanks for any help, > > John Morgensen > > On 12/20/2018 2:14 PM, Robert L. Nuckolls, III wrote: >> At 01:23 PM 12/20/2018, you wrote: >>> >>> >>> Two years ago I had an over-voltage event and the crowbar protection >>> behaved as expected. It popped the 5amp breaker. I had the >>> alternator (Plane Power 60amp internal) repaired and it has behaved >>> normally since then. The alternator stopped working this Sunday. The >>> crimp had failed on the 18ga to 22ga fuse-link. Closer inspection >>> revealed that the insulation under the heat shield on the fuse-link >>> was almost completely gone. >>> >>> Questions: >>> >>> 1. Should I have inspected the fuse-link after the over-voltage >>> incident before putting the plane back in service? >>> >>> 2. Is it acceptable to solder the joint between the 18ga and the >>> 22ga or is a crimp connector required? >> >> I would really like to have that fusible link >> assembly. Can you cut it out and fabricate >> a new one? >> >> When you say "gone" . . . is it melted, charred, >> evaporated? Was it Tefzel wire? >> >> That link normally carries 3A or less. I've >> demonstrated that 22AWG Tefzel will carry >> 20A indefinitely in the open air. >> >> Some combination of factors stacked up to >> cause this particular link to suffer >> damage. A good place to start is careful >> examination of the link. >> >> >> Bob . . . >> John, When you said, ' "Main Power Distribution Bus" bolt to pin 5 on the S700-2-10 switch', did you mean literally, or was that just shorthand for fuselink>18ga>breaker>20ga>pin5 ? Are you absolutely certain that your wiring is an *exact* match for what's shown in Z-13/8? Any chance your OV crowbar got tied to the supply side of the CB, instead of the load side? Are you absolutely sure that nothing whatsoever got tied to that feed, somewhere ahead of the CB? Just spit balling here, but: 22ga wire will carry quite a bit more current than 5A without even damaging the insulation, much less the wire. Burning it twice implies either a much higher load on that wire, or (more likely) a dead short to ground prior to the CB (if the CB is in the circuit). The crowbar circuit could likely survive long enough to fry the wire without damaging the crowbar. If that's happening, that implies either the crowbar is misadjusted, or it's setpoint is drifting, or you're having actual overvoltage events. Do you have data logging of your instruments? Can you check the log for voltage levels over time? Charlie (BTW, top-posting after a bottom-posted reply makes for really hard reading) --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ________________________________ Message 3 _____________________________________ Time: 07:03:55 PM PST US Subject: AeroElectric-List: Re: Fuse-able link From: "user9253" That wire did not burn open from an overload. There was a dead short to ground. Either a wire is shorted to ground or else the Over Voltage Module is tripping (shorting to ground). And that short circuit is upstream from the circuit breaker. In other words, something is wired incorrectly. Or else the circuit breaker is defective. If the wire is connected from the main power bus to pin 5 on the switch, then it is NOT wired according to Z-13/8. The circuit breaker needs to be between the fuselink and the over-voltage module. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=486603#486603 ------------------------------------------------------------------------------------- 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.