---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 02/23/22: 7 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:17 AM - Re: Sizing a B-lead ANL (user9253) 2. 09:03 AM - Re: Sizing a B-lead ANL (Eric Page) 3. 11:16 AM - Re: Sizing a B-lead ANL (johnbright) 4. 11:35 AM - Re: Sizing a B-lead ANL (Robert L. Nuckolls, III) 5. 11:37 AM - Re: Re: Sizing a B-lead ANL (Robert L. Nuckolls, III) 6. 01:43 PM - Re: Sizing a B-lead ANL (Charlie England) 7. 07:48 PM - Re: Sizing a B-lead ANL (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 08:17:42 AM PST US Subject: AeroElectric-List: Re: Sizing a B-lead ANL From: "user9253" https://www.eaton.com/content/dam/eaton/products/electrical-circuit-protection/fuses/data-sheets/bus-ele-ds-2024-anl.pdf The rating of the ANL current limiter should NOT exceed the alternator rating. Alternators are self current limiting. The purpose of the fuse is to protect the battery and electrical system from "B" lead and alternator short circuits. The rating of the fuse should be chosen so that it will never blow while conducting maximum alternator current output. Your friend might consider a maxi fuse. They look like giant ATC fuses. https://m.littelfuse.com/~/media/automotive/datasheets/fuses/passenger-car-and-commercial-vehicle/blade-fuses/littelfuse_maxi_58v_datasheet.pdf -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=506118#506118 ________________________________ Message 2 _____________________________________ Time: 09:03:39 AM PST US Subject: AeroElectric-List: Re: Sizing a B-lead ANL From: "Eric Page" Thanks very much, Joe. I'll pass that along. Eric Read this topic online here: http://forums.matronics.com/viewtopic.php?p=506119#506119 ________________________________ Message 3 _____________________________________ Time: 11:16:55 AM PST US Subject: AeroElectric-List: Re: Sizing a B-lead ANL From: "johnbright" I haven't been able to find a definition or history of current limiters, but, at least in the case of ANL current limiters of the ratings we use, it seems like they are designed so you don't have to calculate how much bigger than the load to size them, just use one placarded for your load. Note a 60A ANL will carry over 100A continuously. Here's what I put on my schematic: Littlefuse MIDI/Bussmann AMI fuses are specified on this schematic for the alternator B leads versus legacy ANL current limiters because they are physically smaller. ANL current limiters with the same rating as the alternator could be used but MIDI fuses of a higher rating are chosen. It is assumed the alternator is capable of 120% of its rated output, this is divided first by 0.75 (nuisance blowing factor per Littelfuse "Fuseology" document) and then by 0.95 (temperature re-rating factor per Littelfuse MIDI data sheet, 170F firewall temperature is assumed). Main alternator: (60 * 1.2) / (0.75 * 0.95) = 101 A, close enough to 100 to choose a 100 A MIDI. Vacuum pad alternator: (35 * 1.2) / (0.75 * 0.95) = 59 A, a 60 A MIDI is chosen. Alternate for alternator B leads is FLW (fuse link wire) 6" long, 4 awg smaller than B lead, PICO brand is common; available from 10 to 20 awg. FLW is a slightly cleaner installation; ANLs, and especially MIDIs, open with less energy. -------- 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://drive.google.com/folderview?id=1u6GeZo6pmBWsKykLNVQMvu4o1VEVyP4K Read this topic online here: http://forums.matronics.com/viewtopic.php?p=506123#506123 ________________________________ Message 4 _____________________________________ Time: 11:35:25 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Sizing a B-lead ANL At 11:35 PM 2/22/2022, you wrote: > >I'm asking for a friend, who is installing a Verner radial engine on >a Kitfox... > >In some of the Z-figures, ANL current limiters are annotated as >"sized to alternator." In others, the annotation refers to Note 10, >which doesn't discuss sizing. On Z-12, the alternator is labeled as >60A, and the ANL is annotated as "ANL60." > >So, should the ANL rating match the alternator nameplate rating as >closely as possible, or slightly exceed it, or is there some other >formula? I didn't find anything specific in the text of the >'Connection, and a search on the forum came up empty as well. ANL devices are EXCEEDINGLY robust http://aeroelectric.com/Mfgr_Data/Fuses_and_Current_Limiters/Bussman/ANL_Specs.pdf An ANL60 will carry over 100A continuously. This tells us that current limiters are designed to mitigate HARD faults (many hundreds of Amps). So picking an ANL equal to or even SMALLER than the alternator is not a sketchy idea. Alternatively, consider a fusible link (4AWG smaller than B-lead). This will serve the same purpose and is often less expensive and more installer-friendly. As the Z-figures evolve, ANL and similar devices are going to be replaced with fusible links. 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 5 _____________________________________ Time: 11:37:13 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Sizing a B-lead ANL At 01:16 PM 2/23/2022, you wrote: > > >I haven't been able to find a definition or history of current >limiters, but, at least in the case of ANL current limiters of the >ratings we use, it seems like they are designed so you don't have to >calculate how much bigger than the load to size them, just use one >placarded for your load. Note a 60A ANL will carry over 100A continuously. > >Here's what I put on my schematic: > >Littlefuse MIDI/Bussmann AMI fuses are specified on this schematic >for the alternator B leads versus legacy ANL current limiters >because they are physically smaller. > >ANL current limiters with the same rating as the alternator could be >used but MIDI fuses of a higher rating are chosen. It is assumed the >alternator is capable of 120% of its rated output, this is divided >first by 0.75 (nuisance blowing factor per Littelfuse "Fuseology" >document) and then by 0.95 (temperature re-rating factor per >Littelfuse MIDI data sheet, 170F firewall temperature is assumed). > >Main alternator: (60 * 1.2) / (0.75 * 0.95) = 101 A, close enough to >100 to choose a 100 A MIDI. > >Vacuum pad alternator: (35 * 1.2) / (0.75 * 0.95) = 59 A, a 60 A >MIDI is chosen. > >Alternate for alternator B leads is FLW (fuse link wire) 6" long, 4 >awg smaller than B lead, PICO brand is common; available from 10 to >20 awg. FLW is a slightly cleaner installation; ANLs, and especially >MIDIs, open with less energy. Exactly. But life is much simpler with fusible links. 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 6 _____________________________________ Time: 01:43:54 PM PST US Subject: Re: AeroElectric-List: Sizing a B-lead ANL From: Charlie England snipped > > Alternatively, consider a fusible link (4AWG > smaller than B-lead). This will serve the same > purpose and is often less expensive and more > installer-friendly. > > As the Z-figures evolve, ANL and similar > devices are going to be replaced with fusible > links. > > > Bob . . . > That's what I did. I confess to using a pair of off-the-shelf Denso internally regulated alternators, with the OV protection on a pair of continuous duty contactors on the firewall. The blue wires in the pic are actually 12awg fusible link wire, doing double duty as interconnects and protection for the 8awg B leads (~2 foot runs). Needless to say, I'm a big fan of using links. Charlie -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ________________________________ Message 7 _____________________________________ Time: 07:48:26 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Sizing a B-lead ANL >That's what I did. I confess to using a pair of off-the-shelf Denso >internally regulated alternators, with the OV protection on a pair >of continuous duty contactors on the firewall. The blue wires in the >pic are actually 12awg fusible link wire, doing double duty as >interconnects and protection for the 8awg B leads (~2 foot runs). > >Needless to say, I'm a big fan of using links. me too . . . The probability of a hard-fault to a b-lead is exceedingly low . . . but FMEA protocols do not consider 'exceedingly low' . . . they ASSUME that if a failure is at all possible, then design mitigation into the system. This is how mission-reliability is promoted . . . mission critical features of the airplane are first rendered non-hazardous and then backed up by a system unlikely to be affect by the same stresses while you finish consuming one tank full of fuel. Hence, NO SYSTEM is really mission- critical irrespective of the MTBF numbers. ANL and similar devices are parts, installation and cost intensive while adding an incalculably small if not zero value to system reliability. So a piece of 'magic wire' with a terminal on one end and splice on the other seems quite practical. 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.