AeroElectric-List Digest Archive

Fri 05/09/14


Total Messages Posted: 9



Today's Message Index:
----------------------
 
     1. 03:18 AM - Re: Re: Fusable link (Robert L. Nuckolls, III)
     2. 06:56 AM - how to build a 16AWG fuse link (Sacha)
     3. 08:55 AM - Re: Re: Fusable link (Jeff Luckey)
     4. 09:08 AM - Re: how to build a 16AWG fuse link (Robert L. Nuckolls, III)
     5. 10:48 AM - Re: How to lose both ignition systems? (Builder_Bill)
     6. 11:36 AM - Re: Re: How to lose both ignition systems? (Robert L. Nuckolls, III)
     7. 02:10 PM - Re: how to build a 16AWG fuse link (Sacha)
     8. 05:11 PM - Re: how to build a 16AWG fuse link (Robert L. Nuckolls, III)
     9. 09:02 PM - When to use Shielded Wire? (Justin Jones)
 
 
 


Message 1


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    Time: 03:18:40 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Fusable link
    > >Not sure what that means... ??? > >If it is "robust" wouldn't it carry enough current to blow the limiter? >Are you suggesting that "welding/burning" aluminum does not draw a >lot of current? >Have you ever tested that hypothesis? Actually, it doesn't. Recall the anecdote about the C90 parting and elevator control cable with a soft fault to a wire. A 40A breaker didn't trip nor was the wire itself seriously damaged. http://tinyurl.com/n3dqkb2 >Even if some of the above is true, a current limiter still could >provide some protection >from a "hard" fault, could it not? Define 'hard' fault . . . and hypothesize how one comes into existence. What kind of circuit closure has to happen to carry hundreds of amps of current? Consider how a contactor is built specific to that goal. Now, how does such a connection happen along the pathway for a fat wire as it travels about the airplane? The #1 failure in wires is simple disconnect. #2 is insulation failure by virtue of mechanical intrusion . . . abrasion or sharp edge cutting due to poor support combined with vibration. What is the quality of first contact? It's tentative, low force, high resistance event that produces some arcing but is generally far short of that required to put the wire at risk or even open it's upstream current limiter. Then there's the probability: #1 failure is rare, #2 several magnitudes more rare, and if a composite airplane, a few magnitudes more rare yet. The few times I've seen the result of a battery cable insulation chaffing and taking the conductor to ground, the fault self cleared when the offending aluminum burned away. When breakers open in airplanes, the most likely cause is failure in the powered device . . . not because of compromised insulation in the wire-run. If you want to put a current limiter in your battery line, by all means. I'm only suggesting that your airplane will be one of a very few in a constellation of tens of thousands. Bob . . .


    Message 2


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    Time: 06:56:38 AM PST US
    From: "Sacha" <uuccio@gmail.com>
    Subject: how to build a 16AWG fuse link
    I'm building a 16 AWG fuse link for a 12AWG wire (the one that goes from the Alternator to the starter contactor in e.g. Z16M). I was thinking of simply solder splicing a piece of 16AWG onto the end of the 12AWG wire and heat-shrinking the whole thing. Is that correct or is there anything else I need to know? The link at http://www.aeroelectric.com/articles/fuselink/fuselink.html says "contact us for manufacturing larger fuselinks than 20AWG" so I was left wondering. Sacha


    Message 3


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    Time: 08:55:16 AM PST US
    From: Jeff Luckey <jluckey@pacbell.net>
    Subject: Re: Fusable link
    =0A=0A=0A=0A________________________________=0A From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>=0ATo: aeroelectric-list@matronics.com =0ASent: Friday, May 9, 2014 3:00 AM=0ASubject: Re: AeroElectric-List: Re: uckolls, III" <nuckolls.bob@aeroelectric.com>=0A=0A=0A>=0A>Not sure what th at means... ???=0A>=0A>If it is "robust" wouldn't it carry enough current t o blow the limiter?=0A>Are you suggesting that "welding/burning" aluminum d oes not draw a =0A>lot of current?=0A>Have you ever tested that hypothesis? =0A=0A=0A- - Actually, it doesn't. Recall the anecdote about=0A- - the C90 parting and elevator control cable with=0A- - a soft fault to a wire. A 40A breaker didn't trip=0A- - nor was the wire itself seriousl y damaged.=0A=0Ahttp://tinyurl.com/n3dqkb2=0A=0A=0A>Even if some of the abo ve is true, a current limiter still could =0A>provide some protection=0A>fr om a "hard" fault, could it not?=0A=0A- - Define 'hard' fault . . . and hypothesize how=0A- - one comes into existence.=0A=0ABob - I think you side stepped the question...=0A=0A".. current limiter still could =0Aprovi de some protection=0Afrom a "hard" fault, could it not? "=0A=0Aregardless o f how the hard fault happens.=0A=0ALet's consider the worst case scenario w here=0Awe have a crash and a hard-fault occurs.=0A=0A=0A=0A- - What kin d of circuit closure has to happen to=0A- - carry hundreds of amps of c urrent? Consider=0A- - how a contactor is built specific to=0A- - t hat goal. Now, how does such a connection=0A- - happen along the pathwa y for a fat wire as=0A- - it travels about the airplane?=0A=0A- - T he #1 failure in wires is simple disconnect.=0A- - #2 is insulation fai lure by virtue of mechanical=0A- - intrusion . . . abrasion or sharp ed ge cutting=0A- - due to poor support combined with vibration.=0A- - What is the quality of first contact? It's tentative,=0A- - low force, high resistance event that produces=0A- - some arcing but is generally far short of that=0A- - required to put the wire at risk or even open =0A- - it's upstream current limiter.=0A=0A- - Then there's the pro bability: #1 failure=0A- - is rare, #2 several magnitudes more rare, an d=0A- - if a composite airplane, a few magnitudes more=0A- - rare y et.=0A=0A- - The few times I've seen the result of a battery=0A- - cable insulation chaffing and taking the conductor=0A- - to ground, the fault self cleared when the offending=0A- - aluminum burned away. When breakers open in=0A- - airplanes, the most likely cause is failure=0A - - in the powered device . . . not because of=0A- - compromised in sulation in the wire-run.=0A=0A- - If you want to put a current limiter in your=0A- - battery line, by all means. I'm only suggesting=0A- - that your airplane will be one of a very few=0A- - in a constellati ==============


    Message 4


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    Time: 09:08:59 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: how to build a 16AWG fuse link
    At 08:09 AM 5/9/2014, you wrote: > >I'm building a 16 AWG fuse link for a 12AWG wire (the one that goes from the >Alternator to the starter contactor in e.g. Z16M). > >I was thinking of simply solder splicing a piece of 16AWG onto the end of >the 12AWG wire and heat-shrinking the whole thing. Is that correct or is >there anything else I need to know? > >The link at http://www.aeroelectric.com/articles/fuselink/fuselink.html says >"contact us for manufacturing larger fuselinks than 20AWG" so I was left >wondering. Solder and shrink would be fine. An alternative would be a COTS automotive offering: http://tinyurl.com/kuroczv I'm going to revise that drawing in the future to put a MAXI fuse holder or perhaps one of these in that location. http://tinyurl.com/kyu8huo I've got some of these in surplus stock. I'll mail you one if you want to go that route. Bob . . .


    Message 5


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    Time: 10:48:14 AM PST US
    Subject: Re: How to lose both ignition systems?
    From: "Builder_Bill" <jonesw@mindspring.com>
    Hello Bob and AEC. Can we re visit this one. I've read the NTSB accident natative, but I need a sketch to follow this builders mistake. Thanks, Bill nuckolls.bob(at)aeroelect wrote: > At 03:29 PM 8/29/2013, you wrote: > > > > > > > > > Bob, I was at your seminar at EAA431Brodhead, WI this Spring. > > > > There was a discussion on an accident involving a Lancair Dual LSE > > Ignition failure. I could not find it in a simple NSTB search > > assuming I even have enough details right to do so. > > > > The builder had supplied each LSE from an independent source, but > > failed to consider something else. Something about fuse & CB's in series maybe? > > > > Can you detail what happened to take down both LSE's? It's likely > > that sketch will be necessary. > > > > > > Yes. That case settled a few weeks ago. I'm going to publish > my reports and demonstration videos that were produced in > support of the technical analysis. I need to 'sanitize' them > a little so as to avoid causing unwarranted discomfort on > the part of the participants. > > In any case, it is unlikely that anyone here on the > List would repeat the error . . . an error that grew out > of a combination of 'redundancy' features stacked on top > of each other combined with a poor selection of components > wherein both systems shared hardware in the power path. > > Run each ignition from a separate protective device on > the battery bus . . . or separate battery busses if there > are two batteries. Simple, direct, no shared hardware > and truly redundant. > > > > > > Bob . . . Read this topic online here: http://forums.matronics.com/viewtopic.php?p=423077#423077


    Message 6


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    Time: 11:36:12 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: How to lose both ignition systems?
    At 12:47 PM 5/9/2014, you wrote: ><jonesw@mindspring.com> > >Hello Bob and AEC. >Can we re visit this one. I've read the NTSB accident natative, but >I need a sketch to follow this builders mistake. > >Thanks, Bill > See N811HB at . . . http://tinyurl.com/ky7szec . . . for a detailed data dump Bob . . .


    Message 7


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    Time: 02:10:22 PM PST US
    Subject: Re: how to build a 16AWG fuse link
    From: Sacha <uuccio@gmail.com>
    Thanks Bob. I was thinking a 30A slow blow fuse (they only exist in Maxi blade sizes) might be appropriate but I can't find one here locally nor an appropriately sized fuse holder. I'd be happy to buy a couple off you if you have some spares (i say a couple as I could use one on one of the circuits on my sailboat too). > On May 9, 2014, at 18:07, "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com> wrote: > > > At 08:09 AM 5/9/2014, you wrote: >> >> I'm building a 16 AWG fuse link for a 12AWG wire (the one that goes from the >> Alternator to the starter contactor in e.g. Z16M). >> >> I was thinking of simply solder splicing a piece of 16AWG onto the end of >> the 12AWG wire and heat-shrinking the whole thing. Is that correct or is >> there anything else I need to know? >> >> The link at http://www.aeroelectric.com/articles/fuselink/fuselink.html says >> "contact us for manufacturing larger fuselinks than 20AWG" so I was left >> wondering. > > Solder and shrink would be fine. An alternative > would be a COTS automotive offering: > > http://tinyurl.com/kuroczv > > I'm going to revise that drawing in the future to put a > MAXI fuse holder or perhaps one of these > in that location. > > http://tinyurl.com/kyu8huo > > I've got some of these in surplus stock. I'll > mail you one if you want to go that route. > > > > > > Bob . . . > > > >


    Message 8


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    Time: 05:11:38 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: how to build a 16AWG fuse link
    At 04:08 PM 5/9/2014, you wrote: > >Thanks Bob. >I was thinking a 30A slow blow fuse (they only exist in Maxi blade >sizes) might be appropriate but I can't find one here locally nor an >appropriately sized fuse holder. Doesn't need to be "slow blo" . . . unless they've upsized your alternator, it's only good for about 20A, A 30A fuse of any style would be find. Bob . . .


    Message 9


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    Time: 09:02:12 PM PST US
    From: Justin Jones <jmjones2000@mindspring.com>
    Subject: When to use Shielded Wire?
    I am getting ready to purchase the wire for my project and need to know what wire to purchase. I have read Bobs articles and plan to purchase 18 and 22 gauge wire. I have an EFIS, Garmin 430, PS Engineering Audio Panel, and a KT76 transponder. I will have electronic ignition and LED lights. My question is what wire needs to be shielded and what wire doesnt need shielding? Is it better to just use shielded wire on everything? Seems like extra weight. Is it better to use shielded wire with numerous separate wires inside? or shielded wire with a single wire inside the shielding? Thanks for the help! Justin




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