Today's Message Index:
----------------------
1. 06:50 AM - Re: Electrical Noise Prevention (messydeer)
2. 08:04 AM - Lightning (Fergus Kyle)
3. 12:48 PM - Re: Electrical Noise Prevention (Robert L. Nuckolls, III)
4. 12:48 PM - Re: Re: Electrical Noise Prevention (Robert L. Nuckolls, III)
5. 12:55 PM - Redundant Power switching (jonlaury)
6. 02:10 PM - Re: Panel Accessible breaker for Mission Critical Item ()
7. 02:55 PM - Re: Electrical Noise Prevention (Tim Andres)
8. 06:25 PM - Re: Redundant Power switching (Richard E. Tasker)
9. 09:14 PM - Re: Redundant Power switching (joe motis)
Message 1
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Subject: | Re: Electrical Noise Prevention |
> 5 strands of 20AWG running from the panel ground
> to the fire wall ground.
Good question, Tim.
I had missed that point. I have a single 10awg wire going from my panel ground
to the firewall, not 5 smaller ones. I used 10awg for my main feeder, so chose
the same size for the ground.
--------
Dan
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=305427#305427
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....just a quick note on personal experience. In the past 50 years or
so, I
(my aircraft) have been struck three times ' thrice too much.
The first was in Vampire fighter on descent to landing at about 20,000
feet
in dense cloud.
Fortunately I was head-down when the light erupted. There was an
instantaneous =92bang=92 followed by a howl which dropped in audio
frequency
when I abruptly reduced power to slow. On the ground, a service panel
had
been blown off ( fuselage was molded wood construction).
Time two was DC-9 enroute the south over S Carolina, in cloud at
31,000..
Bolt of lightning came almost horizontal from passing within about five
miles of a thunderhead (on radar). I saw it out of corner of my eye
coming
in from F/O=92s window. Big bang, no hole found, but followed by cabin
crew
who must know what happened, thus setting off the passengers.
Time three was on final at Heathrow, when unforecasted Cb struck left
side
at rudder pedal level. No system fault found but a neat =BD=94
buttonhole-style
blown through the alu skin. L-1011s are tough.
As a slow learner I determined never to pass within 15 miles of a
thunderhead, except 25 miles when at the freezing level and never had
another attack.
FWIW.
Cheers, Ferg
Message 3
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Subject: | Electrical Noise Prevention |
At 08:25 PM 7/18/2010, you wrote:
>
>Hi Bob and thanks for the help.
>I am trying to understand your comment re: grounds below. Why is the 5X20
>AWG better than a single large wire?
Single wire is single point of failure . . . although
it can also be argued that 5 parallel paths offers the
POTENTIAL for an undetected, latent failure. Further,
at higher frequencies, multiple parallel strands are
lower impedance connection than a single strand (or
one thin, wide strap would be good too). The most
compelling reason was to offer a high probability
for installation success . . . the D-sub connector
accepts 20AWG wires. Going with a single, larger
conductor leaves it up to the installer to fabricate
the joint between the ground wire and the avionics
ground bus.
The short answer is "no single reason . . . but
several significant reasons". But those reasons
are rooted in the features of a D-sub based
ground bus. Other configurations change the
selection of ingredients that go into YOUR
recipe for success.
>And why separate panel and avionics grounds?
Sorry about the vague vernacular. For the purposes
of this discussion, let's use Figure Z15, View B
and move the battery from the nose back to the
rear spar and ground it to the firewall ground
stud. An avionics ground is on the panel sheet
and intended to bring small power/signal wires
to a common ground. The "panel" ground is captive
to the airplane and would take care of grounding
airframe accessories not generally associated with
music, bells, lights and pointers.
> In my case I had planned either a DB 25 or forest of tabs approach
>on the front of the (glass) panel with all local ground needs tied in there,
>then a suitable ground run back to the battery. With a rear mounted battery
>do you then recommend the 5X20AWG run all the way to the back?
The 5x20 configuration presumes a tractor airplane with a forest-of-tabs
on one or both sides of firewall.
>For reference I am building an all electric COZY.
Okay, where are your panel equipment power distribution
busses located? How about doing a sketch on where the
power and ground busses are located along with a list
of loads on each bus.
Bob . . .
Message 4
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Subject: | Re: Electrical Noise Prevention |
At 08:45 AM 7/19/2010, you wrote:
>
>
> > 5 strands of 20AWG running from the panel ground
> > to the fire wall ground.
>
>
>Good question, Tim.
>
>I had missed that point. I have a single 10awg wire going from my
>panel ground to the firewall, not 5 smaller ones. I used 10awg for
>my main feeder, so chose the same size for the ground.
Since you're not using a d-sub avionics ground, leave
the 10AWG in place.
Bob . . .
Message 5
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Subject: | Redundant Power switching |
If I bring separate bus power legs to a DPST to feed a single load, is the current
shared (i.e. halved) on the two poles/switches?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=305471#305471
Message 6
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Subject: | Panel Accessible breaker for Mission Critical |
Item
AOA's are great and I agree with the need. They should be careful
calibrated and even then while helpful, don't bet the bank on them.
Per my original email if you fly a Lancair there is no such thing as a
proficient no flaps landing. It's simply risky. Certainly it can be done
in an emergency. Take whatever precaution you need to ensure the flaps
are working or as I indicated earlier, find a long runway.
Glenn E. Long
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
rgent1224@aol.com
Sent: Thursday, July 15, 2010 6:12 PM
Subject: Re: AeroElectric-List: Panel Accessible breaker for Mission
Critical Item
It happens in flight
Can't reset the breaker or replace the fuse you know this application
has but one remedy install a mechanical AOA and learn how to use it
Always be proficient in no flap landings to a point where it will not be
a big deal to do it. Practice it four or five times a month to maintain
the proficiency Now chew my a__ for saying this Dick
-----Original Message-----
From: ray <raymondj@frontiernet.net>
Sent: Thu, Jul 15, 2010 12:10 pm
Subject: Re: AeroElectric-List: Panel Accessible breaker for Mission
Critical Item
FWIW
Could attempting to deploy flaps at too high a speed result in an
overload resulting in a blown CB?
Could attempting to deploy flaps with an ice buildup result in an
overload resulting in a blown CB?
Could there be any other conditions (bird's nest, or ????) that might be
cleared during flight or by multiple attempts to deploy flaps?
I'm in favor of a resettable CB.
Raymond Julian
Kettle River, MN.
On 07/15/2010 01:23 PM, longg@pjm.com wrote:
>
> Thanks,
>
> Ok, so we're all in agreement that either resetting a breaker or
> replacing a fuse on flaps in flight is completely futile? And were
> quite sure no one in history has recovered from a popped breaker on a
> flap motor?
>
> That makes my decision easy.
>
> Glenn E. Long
>
>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
> robert.mccallum2@sympatico.ca
> Sent: Thursday, July 15, 2010 1:11 PM
> To: aeroelectric-list@matronics.com
> Subject: RE: AeroElectric-List: Panel Accessible breaker for Mission
> Critical Item
>
>
> And further to that , how or why would either a fuse or breaker open
> such that resetting would get the flaps working. If the fuse or
> breaker opens then likely the flap motor or its wiring has failed
> causing the protective device to operate and therefore resetting isn't
> going to restore flap functionality anyway. Protective devices
> normally only operate for just cause, and if you don't repair the root
> cause resetting the device accomplishes nothing other than an
additional trip.
>
>
>
> Bob McC
>
>> From: khorton01@rogers.com
>> Date: Thu, 15 Jul 2010 12:23:06 -0400
>> Subject: Re: AeroElectric-List: Panel Accessible breaker for Mission
>> Critical Item
>> To: aeroelectric-list@matronics.com
>>
>> --> <khorton01@rogers.com>
>>
>> What is your plan to deal with failure of the flap motor? Why
>> wouldn't
>
>> the same plan be appropriate to deal with an open flap motor CB?
>>
>> --
>> Kevin Horton
>> Ottawa, Canada
>>
>>
>>
>> On Thu, Jul 15, 2010 at 11:14,<longg@pjm.com> wrote:
>>>
>>> Goal: to determine if there is added value in being able to reset a
>>> breaker for a mission critical item.
>>>
>>> Assumptions: I have plenty of fuse busses in my airplane (don't sell
>
>>> me on the fuse vs. breaker crap) and only a couple of breakers. I'm
>>> not worried about one more $20 breaker.
>>>
>>> Problem: My aircraft, Lancair Legacy is not designed to land without
>
>>> flaps; not even just for fun. If you do you put yourself in a
>>> situation of a high speed landing with no visibility over the nose.
>>> Flaps fix that problem in that they provide the option of being able
>
>>> to modify the wing cord such that you can see a bit of the runway
>>> during landing. So, all is well when the flap motor has electrons.
>>>
>>> No, there is no Piper J bar on a Legacy. Electric only and no
>>> emergency dump option. The only option is to find a long runway and
> fly it in.
>>>
>>> My question: Am I at negative odds using a fuse which I might have
>>> to fish for if my flaps go out during flight or do I replace that
>>> option with a breaker on the panel?
>>>
>>> Thanks,
>>>
>>> Glenn
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
> ===========
> ===========
> ===========
> ===========
>>
>>
>>
> >
>
>
>
>
>
====================================
====================================
====================================
====================================
Message 7
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Subject: | Electrical Noise Prevention |
Thanks Bob! That makes sense especially when using the D sub.
In my case the fuse blocks will probably be under the Right seat, about a
30" run up to the avionics and various switches. I'm looking into using a
swing down panel to hold the fuse blocks under the panel, but it looks
complicated. There will be 5 breakers in the panel as well. The ground bus
will be in front of the panel in an undetermined location but close to the
avionics stack.
I'm still working on the drawing and will post it soon.
>For reference I am building an all electric COZY.
Okay, where are your panel equipment power distribution
busses located? How about doing a sketch on where the
power and ground busses are located along with a list
of loads on each bus.
Bob . . .
Message 8
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Subject: | Re: Redundant Power switching |
Shared, yes. Halved, not likely. How much of the load each pole of the
switch provides depends on the resistance in each leg. Furthermore, if
you are trying to get by with a switch that is not rated per pole for
your total load you will be overloading it. It is very unlikely that
both poles will switch simultaneously so there will be momentary full
loads on one of the poles. Depending on how many times you plan to
operate the switch and what the load is you may have a problem.
If you are doing it with a properly rated switch to provide a redundant
source of power, you have just created a single point of failure - the
switch.
My $0.02.
Dick Tasker
jonlaury wrote:
> --> AeroElectric-List message posted by: "jonlaury"<jonlaury@impulse.net>
>
> If I bring separate bus power legs to a DPST to feed a single load, is the current
shared (i.e. halved) on the two poles/switches?
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=305471#305471
>
>
>
--
Please Note:
No trees were destroyed in the sending of this message. We do concede, however,
that a significant number of electrons may have been temporarily inconvenienced.
--
Message 9
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Subject: | Re: Redundant Power switching |
Either leg of the switch has the ampacity of the overcurrent protection
device rating available, when either or the sum of both legs reach that
value, the overcurrent device will trip.
It is still the sum of the total load
that will trip the breaker, not how you divide it downstream of the
overcurrent protection.
On Mon, Jul 19, 2010 at 12:54 PM, jonlaury <jonlaury@impulse.net> wrote:
>
> If I bring separate bus power legs to a DPST to feed a single load, is the
> current shared (i.e. halved) on the two poles/switches?
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=305471#305471
>
>
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