---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 04/22/22: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 09:49 AM - FUSIBLE LINKS & CURRENT LIMITERS (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 09:49:37 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: FUSIBLE LINKS & CURRENT LIMITERS Hi Bob, Currently studying fusible links. It's straight forward circuit protection but I'm confused about an example in your book. The third paragraph of Note 4 on page Z7 references fusible links in the shunts on figure Z14, and the fusible lengths are clearly shown in the diagram. However, in the 5th paragraph you reference the fusible-link in the AUX alternator B-lead feed but I don't see any such link in the diagram. I do see what appears to be a fuse labeled MAX30 at the aux batt contactor. Is this the fusible link? While the MAX30 is fusible circuit protection it is not, by definition, a fusible link. It is a member of a robust MAX family of plastic fuses. Note 10 says alternator B-lead protection is best done with current limiters. Is there any difference between a current limiter and a fusible link? Only in their general time-to-function characteristics. Fusible links are generally rather slow to operate and are intended to stand off effects of a 'hard' (typically battery driven) faults. They are quite robust and unlike fuses, are not vulnerable to thermal "hammering". Yes, a MAX30 fuse is shown in the b-lead of a 20A alternator (de-rated by 30% or so). Fusible links are generally preferred in this application. Stone simple, low parts count, spliced into the feeder with reliability exceeded only by the wire itself. But de-rated fuse serves the same design goal even tho clumsy to implement compared to the fusible link. And finally, help me understand the fusible link between the buss and master switch in Z11, but there is no fusible link in this circuit in Z12. Are you talking about the link protecting the feeder out to the alternator field circuit breaker? There's a link in that feeder for both drawings. A lot to absorb, trying to understand as best I can. Thanks again. No problem. 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.