AeroElectric-List Digest Archive

Thu 05/07/15


Total Messages Posted: 10



Today's Message Index:
----------------------
 
     1. 08:27 AM - Re: UN-FUSED MAIN BUS FEEDER (user9253)
     2. 09:02 AM - Re: UN-FUSED MAIN BUS FEEDER (user9253)
     3. 09:06 AM - Re: Re: UN-FUSED MAIN BUS FEEDER (Jeff Luckey)
     4. 09:10 AM - Re: Re: UN-FUSED MAIN BUS FEEDER (Robert L. Nuckolls, III)
     5. 09:11 AM - Alternator Position (michaelrorth)
     6. 09:40 AM - Re: Alternator Position (Robert L. Nuckolls, III)
     7. 11:03 AM - Re: Alternator Position (Michael Orth)
     8. 11:10 AM - Re: Alternator Position (Neal George)
     9. 11:41 AM - Re: Alternator Position (Robert L. Nuckolls, III)
    10. 04:38 PM - Re: Active VOR antenna (Robert L. Nuckolls, III)
 
 
 


Message 1


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    Time: 08:27:43 AM PST US
    Subject: Re: UN-FUSED MAIN BUS FEEDER
    From: "user9253" <fransew@gmail.com>
    Since there is already an ANL fuse installed to protect the alternator "B" lead, why not use that same fuse to protect the main power bus feeder? See attached drawing. One fuse can protect two circuits with no weight or cost penalty. Of course if the alternator shorts out and blows the fuse, power is lost to the main bus. That is unlikely to happen. And if it does, the pilot can turn on the E-BUS switch (not shown on the drawing for simplicity). Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=441831#441831 Attachments: http://forums.matronics.com//files/main_anl_fuse_104.jpg


    Message 2


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    Time: 09:02:21 AM PST US
    Subject: Re: UN-FUSED MAIN BUS FEEDER
    From: "user9253" <fransew@gmail.com>
    Obviously two circuits should not share the same fuse if there are loads on either circuit that are critical to flight safety, for instance retractable landing gear or landing lights or etc. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=441832#441832


    Message 3


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    Time: 09:06:53 AM PST US
    From: Jeff Luckey <jluckey@pacbell.net>
    Subject: Re: UN-FUSED MAIN BUS FEEDER
    Joe, You put your finger right on it - you don't want trouble with the alternato r wire to kill the whole system.=C2- As we all know, the likelihood of failure events is difficult to quantify. Something to consider is that the big wire that goes out to the alternator is in a pretty hostile environment.=C2- Lots of heat, vibration, sharp ed ges, (clumsy mechanics), etc. The additional cost to add a second current limiter is so small. BTW - When the occasion presents itself, I have been asking friends & colle agues to send me wiring diagrams of airplanes they are flying or training i n, and have found, in that small sample, all aircraft use current limiters in the primary feed line. -Jeff On Thursday, May 7, 2015 8:43 AM, user9253 <fransew@gmail.com> wrote: Since there is already an ANL fuse installed to protect the alternator "B" lead, why not use that same fuse to protect the main power bus feeder?=C2 - See attached drawing.=C2- One fuse can protect two circuits with no w eight or cost penalty.=C2- Of course if the alternator shorts out and blo ws the fuse, power is lost to the main bus.=C2- That is unlikely to happe n.=C2- And if it does, the pilot can turn on the E-BUS switch (not shown on the drawing for simplicity). Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=441831#441831 Attachments: http://forums.matronics.com//files/main_anl_fuse_104.jpg - S - - =C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Admin.


    Message 4


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    Time: 09:10:31 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: UN-FUSED MAIN BUS FEEDER
    At 10:26 2015-05-07, you wrote: Since there is already an ANL fuse installed to protect the alternator "B" lead, why not use that same fuse to protect the main power bus feeder? See attached drawing. One fuse can protect two circuits with no weight or cost penalty. Of course if the alternator shorts out and blows the fuse, power is lost to the main bus. That is unlikely to happen. And if it does, the pilot can turn on the E-BUS switch (not shown on the drawing for simplicity). Circuit protection has TWO functions: (1) Protect associated wiring and (2) prevent a failure from propagating across multiple systems. The B-lead protection assumes that probability of a short in alternator diodes, while small, is not zero. Hence, b-lead protection. If that device WERE called upon to do it's job, it would disconnect both the alternator and main bus feeder . . . a condition contrary to design goals. A century of lessons learned suggest that "protection" for properly installed bus feeders is unnecessary. I've seen "main breakers" installed in these feeders on numerous OBAM aircraft schematics over the years. Invariably, they are installed on the panel at the junction of the main bus and the feed line. IF there were any serious threat to a bus feeder, protection would have to be installed at the OTHER end. But you will find no such protection on any TC aircraft I'm aware of. It's a function of FMEA and probabilities. Got into a similar discussion with a gray- beard yesterday. He was an employee of one of my customers. I was talking about the practice of paralleling multiple pins in a connector for the purpose of boosting current carrying capacity . . . with the caveat that each of the paralleled pins needed a 'ballasting resistor' in the form of a 12" length of wire. He offered up the standard argument, "But you cannot detect a latent failure of one pin." "True. But you just did a failure analysis on this system. After all the magic numbers were stirred into the reliability stew, you came up with a one-failure-in-10-to-the-minus- amazing number." "Yes," says he. "Okay, here is a command signal pin right next to my cluster of paralleled pins." "Okay." "A failure in that single pin has the ability to take the system down." "Yeah." "But your probability stew says this single pin offers so little risk for failure that the 10-to-the-minus-amazing numbers for the whole system are not challenged." "Yeaahhh . . ." "Okay, how is one pin paralleled with five others any different?" The conversation got real quiet there. They went off to consider this further. Had this same conversation with a Navy techno-wiennie about 20 years ago. That conversation only lasted about 10 minutes. Emacs! The first flight of this vehicle featured a power distribution box that routed 25 amp feeders through D-sub connectors. Emacs! It's all about properties of materials and management of energy . . . Bob . . .


    Message 5


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    Time: 09:11:03 AM PST US
    Subject: Alternator Position
    From: "michaelrorth" <mosurf@xplornet.com>
    Hello All, Is it acceptable to move a (now) horizontally-mounted to a vertical-mounted position? I'm not concerned with the electrical operation of the alternator but rather the bearing points of the rotor will change from two to one. Thanks, Michael Read this topic online here: http://forums.matronics.com/viewtopic.php?p=441834#441834


    Message 6


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    Time: 09:40:27 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Alternator Position
    At 11:10 2015-05-07, you wrote: > >Hello All, > >Is it acceptable to move a (now) horizontally-mounted to a >vertical-mounted position? > >I'm not concerned with the electrical operation of the alternator >but rather the bearing points of the rotor will change from two to one. > >Thanks, > >Michael What kind of alternator are we talking about? Bob . . .


    Message 7


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    Time: 11:03:47 AM PST US
    From: "Michael Orth" <mosurf@xplornet.com>
    Subject: Re: Alternator Position
    Hi Bob, Actually, I must revise my original post. I have a generator..not an alternator. Of course, it is buried by other equipment and I am unable to make out the nomenclature tag without extensive dismantling. The Parts Manual is mum on the subject of manufacturer. The generator is 25 amps and externally regulated. It is currently mounted on a Continental IO-470-L. Beech Baron. It is belt-driven. Thanks, Michael -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- -----Original Message----- From: Robert L. Nuckolls, III Sent: Thursday, May 7, 2015 9:39 AM Subject: Re: AeroElectric-List: Alternator Position <nuckolls.bob@aeroelectric.com> At 11:10 2015-05-07, you wrote: ><mosurf@xplornet.com> > >Hello All, > >Is it acceptable to move a (now) horizontally-mounted to a vertical-mounted >position? > >I'm not concerned with the electrical operation of the alternator but >rather the bearing points of the rotor will change from two to one. > >Thanks, > >Michael What kind of alternator are we talking about? Bob . . . ----- No virus found in this message. Checked by AVG - www.avg.com


    Message 8


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    Time: 11:10:53 AM PST US
    From: Neal George <ngeorge@continentalmotors.aero>
    Subject: Alternator Position
    Michael - Give me a call and let's discuss. Neal George Tech Support Continental Motors 888-826-5465 Do not archive --> <mosurf@xplornet.com> Hi Bob, Actually, I must revise my original post. I have a generator..not an alternator. Of course, it is buried by other equipment and I am unable to make out the nomenclature tag without extensive dismantling. The Parts Manual is mum on the subject of manufacturer. The generator is 25 amps and externally regulated. It is currently mounted on a Continental IO-470-L. Beech Baron. It is belt-driven. Thanks, Michael


    Message 9


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    Time: 11:41:52 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Alternator Position
    At 13:01 2015-05-07, you wrote: > >Hi Bob, > >Actually, I must revise my original post. > >I have a generator..not an alternator. >Of course, it is buried by other equipment and I am unable to make >out the nomenclature tag without extensive dismantling. >The Parts Manual is mum on the subject of manufacturer. >The generator is 25 amps and externally regulated. >It is currently mounted on a Continental IO-470-L. Beech Baron. >It is belt-driven. > >Thanks, >Michael Interesting. As Neal has suggested, he may be able to offer advise that's more application specific. But I am curious as to how the installation became 'vertical'. I can't imagine that it would make any difference for bearings. While there are such things as THRUST bearings designed to take rated loads axially oriented to the shaft, a ball bearing still has significant performance for axial loading. A major force on the belt driven generator is belt tension. I would imagine armature weight to be on the order of 1/3 or less the belt force. The force vector on the bearing would move out of the bottom of the races . . . but they're hard there too. The weakest mechanical link in a generator is brush-wear. I suspect you'll be replacing brushes at much shorter intervals than for any other reason. Once you have the machine off the airplane for attention, you might as well replace bearings at the same time . . . they're probably cheaper than the brushes! But give Neal a buzz and let us know what you discover. Bob . . .


    Message 10


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    Time: 04:38:35 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Active VOR antenna
    At 15:43 2015-04-24, you wrote: >Bob, > >Have you been able to assess the active VOR >antenna? Were about 30 days from first >flight and really need a retrofit VOR antenna >solution for this bird as we discussed. What is the length of cable from the end of the antenna to your receiver? Bob . . .




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