Today's Message Index:
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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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Subject: | Re: UN-FUSED MAIN BUS FEEDER |
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
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Subject: | Re: UN-FUSED MAIN BUS FEEDER |
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
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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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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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Subject: | Alternator Position |
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
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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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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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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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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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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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