---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 06/14/21: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:49 AM - Re: "Contactor Questions" now CONTACTOR AUTOPSY (Robert L. Nuckolls, III) 2. 09:49 AM - Re: Locking 3P switch? (johnbright) ________________________________ Message 1 _____________________________________ Time: 08:49:31 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: "Contactor Questions" now CONTACTOR AUTOPSY At 11:19 AM 6/12/2021, you wrote: >So there I am rummaging=C2 thru 30 years worth of >things I kept in case I need them...hhhhmmmm >So a contactor ends up in my grubby paws, and I >decide to strip it, 'cause that's what BN would do! lol Good work sir! Thank you for sharing. >Wear patterns on the contacts are clearly >visible, but what I noticed is that with the >factory assembly process, the contacts are >slightly off the horizontal, so the plane of >contact is not parallel=C2 with the contact >disc....accidental? I think not..when you >tighten the outer nut the contact turns until it >hits the coil housing, unless you wedge something in there to prevent turning. This is a fundamental weakness in contactors with 'double-nut' fat terminals as opposed to those captive to molded, non-metalic housings. It's a really good idea to put a wrench on the inside nut and apply opposing torque while tightening the outside nut. I've encountered several contactor failures where the fat terminals were twisted out of alignment during installation. This is not necessarily an automatic precursor to failure . . . but it sure elevates risk. 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: 09:49:53 AM PST US Subject: AeroElectric-List: Re: Locking 3P switch? From: "johnbright" Re "N87BP_Engine_Bus_Detail.pdf" of 11 June 2021 I'm not seeing a failure mode that keeps the engine running if the SDS CPI-2 backup power wires are connected to the engine bus. There IS an SPOF in the form of the single connection to the engine bus. The Bussmann 15600 fuse block can be modified to add a 2nd stud... ref attached three photos. The diode feed from the main bus goes to one stud and the relay feed from the battery goes to the other stud. -------- John Bright, RV-6A, at FWF, O-360 Z-101 single batt dual alt SDS EM-5-F. john_s_bright@yahoo.com, Newport News, Va https://docs.google.com/document/d/1YOtPiA3AdUsQEYR4nodBESNAo21rxdnx4pFs7VxXfuI/edit?usp=sharing Read this topic online here: http://forums.matronics.com/viewtopic.php?p=502366#502366 Attachments: http://forums.matronics.com//files/bussmann_15600_fuse_block_add_a_2nd_stud_photo_1_of_3_956.jpg http://forums.matronics.com//files/bussmann_15600_fuse_block_add_a_2nd_stud_photo_2_of_3_949.jpg http://forums.matronics.com//files/bussmann_15600_fuse_block_add_a_2nd_stud_photo_3_of_3_148.jpg ------------------------------------------------------------------------------------- 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.