---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 04/27/20: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:48 AM - Re: Preliminary tests on modern fuse link wire (bcone1381) 2. 08:54 AM - Re: Preliminary tests on modern fuse link wire (user9253) 3. 09:11 AM - Re: Bose Headset Replacement Plug (Werner Schneider) 4. 09:26 AM - Re: Re: Preliminary tests on modern fuse link wire (Robert L. Nuckolls, III) 5. 10:02 AM - Re: Re: Preliminary tests on modern fuse link wire (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 05:48:25 AM PST US Subject: AeroElectric-List: Re: Preliminary tests on modern fuse link wire From: "bcone1381" Humm. Concerning the B lead wire size. In the above case, the expected load is 30A, the Alternator is 40A. A typical wire size on your Z-diagrams is 4 to 6 AWG The proper size from the wire table for 30A is 10 AWG, but for 40A its 8 AWG. Since you say use 10 AWG for the B-lead, can I say the authoritative rule for B-lead wire is the Load Analysis, not the Z-diagram or the Alternator output? -------- Brooks Cone Bearhawk Patrol Kit Build Read this topic online here: http://forums.matronics.com/viewtopic.php?p=496064#496064 ________________________________ Message 2 _____________________________________ Time: 08:54:26 AM PST US Subject: AeroElectric-List: Re: Preliminary tests on modern fuse link wire From: "user9253" If debating two sizes, I would go with the larger size. Do not forget battery charging current. And larger wire might slightly reduce alternator whine in vulnerable loads. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=496069#496069 ________________________________ Message 3 _____________________________________ Time: 09:11:33 AM PST US Subject: Re: AeroElectric-List: Bose Headset Replacement Plug From: Werner Schneider --- MIME Errors - No Plain-Text Section Found --- A message with no text/plain MIME section was received. The entire body of the message was removed. Please resend the email using Plain Text formatting. HOTMAIL is notorious for only including an HTML section in their client's default configuration. If you're using HOTMAIL, please see your email application's settings and switch to a default mail option that uses "Plain Text". --- MIME Errors No Plain-Text Section Found --- ________________________________ Message 4 _____________________________________ Time: 09:26:58 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Preliminary tests on modern fuse link wire At 07:47 AM 4/27/2020, you wrote: > >Humm. Concerning the B lead wire size. > >In the above case, the expected load is 30A, the Alternator is 40A. understand >A typical wire size on your Z-diagrams is 4 to 6 AWG >The proper size from the wire table for 30A is 10 AWG, >but for 40A its 8 AWG. 'Proper' is not a term carved in stone. As explained in chapter 8 and illustrated in Figure 8-4 and demonstrated in the bench experiment at https://tinyurl.com/6qr72fr backed up with specifications offered at: https://tinyurl.com/y88kyypu The operating current for a wire is based on satisfactory insulation temperatures in the application being configured. Take a peek at qualification temperatures in the cited wire spec . . . the wire has to stand off various abuses at 200C. As shown in Figure 8-4, a 10AWG wire will rise 30C with 45A of current flow. With 150C wire, this means that our b-lead would not be pushed beyond recommended limits with an ambient temperature of 120C. There are no sustained conditions under the cowl that would produce risk to the 10AWG b-lead at 45A. From a voltage drop perspective 10AWG is 0.001 ohms per foot; a 3-foot b-lead would drop 0.045 volts at 45A . . . also no big deal. Further, the only time you would even come close to loading this alternator to near full output would be in cruise . . . buckets of cooling air coming in. Wire tables are exceedingly conservative recommendations unlikely to create hazards for situations where the system integrator is on solid, low-risk ground. But this does not preclude one from considering departures from the table values. In this case, I considered the availability of commercial off the shelf fusible links and found that 14AWG was a pretty common size for the largest link. Okay, that protects a 10AWG wire. Question: Would a 10AWG wire be at risk when used in the situation we're discussing? I concluded that it would not. >Since you say use 10 AWG for the B-lead, can I say the >authoritative rule for B-lead wire is the Load Analysis, >not the Z-diagram or the Alternator output? The tables are not 'authoritative' for anything except the special case which created the tables. The plots in Figure 8-4 are helpful for examining other cases. I've always been a bit queasy working on cars and taking note of the wire and fuse sizes selected for various tasks. Sometimes the fuses seem just a bit 'too big' and/or the wires just a bit 'too small'. But electrical fires having root cause in insulation failure are rare if not non-existent. The folk in Detroit have to be pretty careful with their trade-offs between cost/performance/risk. They produce cars by the millions . . . their exposure for professional malfeasance is pretty sobering! Bob . . . ________________________________ Message 5 _____________________________________ Time: 10:02:12 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Preliminary tests on modern fuse link wire At 10:50 AM 4/27/2020, you wrote: > >If debating two sizes, I would go with the larger size. >Do not forget battery charging current. Battery charging current is part of the alternator's load at the b-terminal. Battery demands are not a component of the design calculation. > And larger wire might slightly reduce alternator whine in vulnerable loads. There are no "loads" particularly vulnerable to alternator whine. The vast majority of alternator noise issues are conductivly coupled to the victim's low level signal paths via ground loops. A tiny percentage are magnetically coupled in wire bundles. See my narrative on alternator whine in my newly acquired Plymouth Voyager back about 1990. The b-lead on my 87 GMC pick-em-up truck is 10AWG. It'a about 18" long and runs from the b-term right to the battery(+) terminal. The alternator options INCLUDE machines up to 90A in output. At 90a, and 0.0015 milliohms of wire, the voltage drop would be 135 millivolts and dissipate 12 watts. No doubt the wire would warm up pretty good . . . but the thing is hanging out in the air right behind the cooling air flow out of the radiator. This lead doesn't event have a fusible link . . . it just hangs out in the air. Bob . . . ------------------------------------------------------------------------------------- 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.