Today's Message Index:
----------------------
1. 05:34 AM - Re: Re: ARINC Wiring Shield? (Henador Titzoff)
2. 10:05 AM - Wires that pass near a Magnetometer (bcone1381)
3. 11:40 AM - Re: Re: ARINC Wiring Shield? (Robert L. Nuckolls, III)
4. 12:08 PM - Re: Wires that pass near a Magnetometer (Robert L. Nuckolls, III)
5. 12:37 PM - Re: Wires that pass near a Magnetometer (Robert L. Nuckolls, III)
6. 12:38 PM - Re: Wires that pass near a Magnetometer (Robert L. Nuckolls, III)
7. 12:44 PM - Re: Wires that pass near a Magnetometer (Robert L. Nuckolls, III)
8. 12:45 PM - Re: Wires that pass near a Magnetometer (Robert L. Nuckolls, III)
9. 01:18 PM - Re: Re: ARINC Wiring Shield? (Kelly McMullen)
10. 03:54 PM - Re: Wires that pass near a Magnetometer (bcone1381)
11. 05:11 PM - Re: Re: ARINC Wiring Shield? (Henador Titzoff)
12. 07:54 PM - Re: Re: ARINC Wiring Shield? (Robert L. Nuckolls, III)
13. 08:00 PM - Re: Re: Wires that pass near a Magnetometer (Robert L. Nuckolls, III)
14. 08:24 PM - Z-13/8 review request (jcarne)
15. 08:57 PM - Re: Z-13/8 review request (Charlie England)
Message 1
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| Subject: | Re: ARINC Wiring Shield? |
"Yeah . . . probably . . . but about the only way=C2- you can buy twisted
pair is under a shield."
This is not quite true, Bob.=C2- There are several examples of twisted wi
re cables that do not have shields.=C2- The most ubiquitous example is Et
hernet, also known as 10BASE-T, 100BASE-T and 1000BASE-T. These three media
are basically the same but are modified slightly to accommodate faster and
faster data transmission.=C2- They are defined in the IEEE 802 standard.
=C2-These 3 cables are hardly distinguishable by the naked eye except for
color coded plastic jackets, and they contain no shielding.=C2-They only
contain 4 twisted wire pairs that are held in close proximity to each othe
r by the jacket.
It was determined by defense contractors back in the 1980s that twisted wir
es will accomplish two things.=C2- First, each pair keeps its magnetic fi
eld to a bare minimum by ensuring that the twisted wires are in close proxi
mity to each other.=C2- As current flow in one direction on one wire, its
mate carries the return current back to its source.=C2- The resulting op
posite magnetic fields from each wire cancel each other out due to their cl
ose proximity. This means that their twin magnetic fields do not interfere
with the other twisted wire pairs' magnetic fields.=C2- Second, if the tw
isted wire pair transmitters and receivers are differential instead of sing
le-ended, they can reject offending magnetic fields, because the injected v
oltages are the same in the two wires, due to their proximity to each other
. The differential receiver sees the offending voltages but rejects them du
e to its design.
The major defense contractors have known about this technique for a while n
ow and have implemented them in both wire cables and printed circuit boards
to reduce the chances of electromagnetic interference.=C2- Minor defense
contractors and commercial companies have taken a much longer time to disc
over how to transmit signals from point A to B and have made painstaking mi
stakes that have affected their schedules and reliability tremendously.=C2
- In many cases, they still haven't figured it out.
All of this came about because of increasing signal speeds.=C2- Most peop
le think of signal speeds in terms of clock speed.=C2- The correct way of
looking at it is the signal's rising and edge times. The true electromagne
tic spectra of these rising and falling edges can be studied by use of the
Fourier transform.=C2- This transform will reconstruct the edges using di
screte frequency spectra, whose frequencies extend harmonically beyond the
clock speed. In other words, the frequencies generated by a simple clock or
signal pulse go way beyond what you will see on the signal's oscilloscope
waveform.=C2- Then by using Maxwell's equations, one can study how the fi
elds radiate out and come up with solutions.
Today's technology is much different than 1980s technology, with spectra go
ing into the microwave region. In the commercial world, major companies lik
e Intel have had to develop and rely on tools that study both motherboard a
nd IC layouts to minimize interference from closely placed components.=C2
- They have developed techniques like microstrip and stripline to minimiz
e electromagnetic interference, much like what twisted wire pairs do.=C2-
They do not rely on shielding, because they're keeping each signal's offen
ding magnetic fields to a bare minimum, even when located microns from each
other.=C2- The two methods mentioned above were borrowed from the radar
world. In other words, it took RF engineers to solve computer engineers' pr
oblems as speeds increased.
In my opinion, the EFIS manufacturers are behind the 8-ball, mostly because
their engineers have not been exposed to what I say above.=C2- Furthermo
re, these companies are really run by software engineers who are living in
the ideal world and have no clue about signals and their spectra and how to
control them. I've seen several examples of EFIS manufacturers solve "glit
ches" with software.=C2- These software patches are only band-aids and co
ntinue to proliferate in future designs, because they don't truly understan
d the problem.=C2- As band-aids accumulate, the EFIS functionalities beco
me even more quirky.=C2- I see this in many other products, and people ex
plain them away as "just a glitch."
Shields are used by the "experts" for two reasons.=C2- One is to provide
a more uniform controlled impedance to transmit RF power and receive weak R
F energy.=C2- Two is for physical integrity such as the wire telling the
ignition mag to turn on and off. That wire could easily be replaced with a
twisted wire pair, but shielding provides better physical protection.=C2-
You could run it in a PVC pipe and accomplish the same thing.
I know this all sounds mysterious to most people, but I know for a fact tha
t 3 defense manufacturers started looking at signal integrity problems star
ting in the 1980s when things started getting faster, and glitches started
popping up.=C2- These 3 companies wrote design manuals for their engineer
s to follow.=C2- These books were cook books designed to avoid previously
made mistakes. They actually have review boards that ensure the guidelines
were followed.=C2- If you don't follow them, you better have a damn good
reason why you didn't. I know of several cases where design engineers actu
ally came up with better ideas, and the design manuals were revised.=C2-
In all cases, reliability and problem free operation overrode other factors
.
Henador Titzoff
On Wednesday, August 28, 2019, 02:01:55 AM EDT, Robert L. Nuckolls, III
<nuckolls.bob@aeroelectric.com> wrote:
At 08:34 AM 8/27/2019, you wrote:
--> AeroElectric-List messageposted by: "dj_theis" <djtheis58@gmail.com>
Hi Art,
I think it might be a case of =C3=A2=82=AC=C5=93belt and suspenders=C3
=A2=82=AC=EF=BD but in theindustrial arena, it is not uncommon for ve
ndors implementing CANnetworks to recommend twisted + shieldedcabling.
=C2- Yeah . . . probably . . . but about the only way
=C2- you can buy twisted pair is under a shield. I've
=C2- probably got a few thousand feed of 2x22S . . .
=C2- how many feet do you need . . . send me a mailing
=C2- address
=C2- Bob . . .
Message 2
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| Subject: | Wires that pass near a Magnetometer |
I am building a Bearhawk Patrol and am installing the wiring in the wing to accommodate
Whelen LED wing tip nave lights and strobes, plus a Garmin Magnetometer.
I need to comply with the Garmin instructions which say the electrical conductors
passing more than 100mA current should be a twisted shielded pair if
they pass within 10 feet of the magnetometer.
The Whelen lights have four wires. One ground wire, one sync wire to sync up the
strobes, and two 12Vdc power wires, one for the Nav Light, and one for the
Strobe.
In order to apply Garmin's "Twisted Sheilded Pair" demand, am I right in thinking
I should run three twisted shield pairs, one for each power wire, and one for
the sync, having each of these three wires twisted with a ground wire? Then
I think I'll run the ground and shielding to the ground block at the inside
of my firewall.
--------
Brooks Cone
Bearhawk Patrol Kit Build
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=491095#491095
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| Subject: | Re: ARINC Wiring Shield? |
>This is not quite true, Bob. There are several examples of twisted
wire cables that do not have shields. The most ubiquitous example is
Ethernet, also >known as 10BASE-T, 100BASE-T and 1000BASE-T.
But where would we find Cat5 cable
on an airplane? I was speaking of wire
I might pull from inventory at Beech . . .
Bob . . .
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| Subject: | Re: Wires that pass near a Magnetometer |
At 12:03 PM 8/28/2019, you wrote:
>
>I am building a Bearhawk Patrol and am installing the wiring in the
>wing to accommodate Whelen LED wing tip nave lights and strobes,
>plus a Garmin Magnetometer. I need to comply with the Garmin
>instructions which say the electrical conductors passing more than
>100mA current should be a twisted shielded pair if they pass within
>10 feet of the magnetometer.
>
>The Whelen lights have four wires. One ground wire, one sync wire
>to sync up the strobes, and two 12Vdc power wires, one for the Nav
>Light, and one for the Strobe.
>
>In order to apply Garmin's "Twisted Sheilded Pair" demand, am I
>right in thinking I should run three twisted shield pairs, one for
>each power wire, and one for the sync, having each of these three
>wires twisted with a ground wire? Then I think I'll run the ground
>and shielding to the ground block at the inside of my firewall.
No . . . was there any wire supplied with
the Whelen parts? Just keeping the
4 wires together under a single jacket
should suffice. The Whelen kits used to
include wing wire (used to be twisted
trio under shield) . . . any
wire included these days?
Bob . . .
Message 5
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| Subject: | Re: Wires that pass near a Magnetometer |
At 12:03 PM 8/28/2019, you wrote:
>
>I am building a Bearhawk Patrol and am installing the wiring in the
>wing to accommodate Whelen LED wing tip nave lights and strobes,
>plus a Garmin Magnetometer. I need to comply with the Garmin
>instructions which say the electrical conductors passing more than
>100mA current should be a twisted shielded pair if they pass within
>10 feet of the magnetometer.
>
>The Whelen lights have four wires. One ground wire, one sync wire
>to sync up the strobes, and two 12Vdc power wires, one for the Nav
>Light, and one for the Strobe.
>
>In order to apply Garmin's "Twisted Sheilded Pair" demand, am I
>right in thinking I should run three twisted shield pairs, one for
>each power wire, and one for the sync, having each of these three
>wires twisted with a ground wire? Then I think I'll run the ground
>and shielding to the ground block at the inside of my firewall.
No . . . was there any wire supplied with
the Whelen parts? Just keeping the
4 wires together under a single jacket
should suffice. The Whelen kits used to
include wing wire (used to be twisted
trio under shield) . . . any
wire included these days?
Bob . . .
Message 6
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| Subject: | Re: Wires that pass near a Magnetometer |
At 12:03 PM 8/28/2019, you wrote:
>
>I am building a Bearhawk Patrol and am installing the wiring in the
>wing to accommodate Whelen LED wing tip nave lights and strobes,
>plus a Garmin Magnetometer. I need to comply with the Garmin
>instructions which say the electrical conductors passing more than
>100mA current should be a twisted shielded pair if they pass within
>10 feet of the magnetometer.
What model of tip lights are you installing?
Bob . . .
Message 7
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| Subject: | Re: Wires that pass near a Magnetometer |
At 12:03 PM 8/28/2019, you wrote:
>
>I am building a Bearhawk Patrol and am installing the wiring in the
>wing to accommodate Whelen LED wing tip nave lights and strobes,
>plus a Garmin Magnetometer. I need to comply with the Garmin
>instructions which say the electrical conductors passing more than
>100mA current should be a twisted shielded pair if they pass within
>10 feet of the magnetometer.
>
>The Whelen lights have four wires. One ground wire, one sync wire
>to sync up the strobes, and two 12Vdc power wires, one for the Nav
>Light, and one for the Strobe.
>
>In order to apply Garmin's "Twisted Sheilded Pair" demand, am I
>right in thinking I should run three twisted shield pairs, one for
>each power wire, and one for the sync, having each of these three
>wires twisted with a ground wire? Then I think I'll run the ground
>and shielding to the ground block at the inside of my firewall.
No . . . was there any wire supplied with
the Whelen parts? Just keeping the
4 wires together under a single jacket
should suffice. The Whelen kits used to
include wing wire (used to be twisted
trio under shield) . . . any
wire included these days?
Bob . . .
Message 8
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| Subject: | Re: Wires that pass near a Magnetometer |
At 12:03 PM 8/28/2019, you wrote:
>
>I am building a Bearhawk Patrol and am installing the wiring in the
>wing to accommodate Whelen LED wing tip nave lights and strobes,
>plus a Garmin Magnetometer. I need to comply with the Garmin
>instructions which say the electrical conductors passing more than
>100mA current should be a twisted shielded pair if they pass within
>10 feet of the magnetometer.
What model of tip lights are you installing?
Bob . . .
Message 9
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| Subject: | Re: ARINC Wiring Shield? |
Well, my Dynon Skyview screens use Cat5 wire between the 2 screens to
sync data updates and common data like altimeter setting, etc. Not
required but eases syncing of things. Otherwise, no, I don't think of
any uses for ethernet cabling in aircraft.
On 8/28/2019 11:37 AM, Robert L. Nuckolls, III wrote:
>
> >This is not quite true, Bob. There are several examples of twisted
> wire cables that do not have shields. The most ubiquitous example is
> Ethernet, also >known as 10BASE-T, 100BASE-T and 1000BASE-T.
>
> But where would we find Cat5 cable
> on an airplane? I was speaking of wire
> I might pull from inventory at Beech . . .
>
> Bob . . .
>
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| Subject: | Re: Wires that pass near a Magnetometer |
The Whelen product is called Orion 600. Model number is OR6001. The light has
a pig tail on it, no other wiring. Here is a link to the installation guide.
https://www.whelen.com/install/146/14662.pdf
--------
Brooks Cone
Bearhawk Patrol Kit Build
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=491105#491105
Message 11
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| Subject: | Re: ARINC Wiring Shield? |
I used Ethernet cable as an example of twisted wire without a shield being
in use.
For aircraft use, twisted wire pairs without a shield are easy to find - th
ey're in in Beech inventory.=C2- All you do is twist 2 same length Tefzel
wires by holding one end in a vise and putting the other 2 ends in a drill
.=C2- The drill will twist them together.=C2- Remember that the wires d
o not have to be tightly wound, which makes them awkward to work with and a
dds weight.=C2- They only have to be wound enough to keep them in close p
roximity.=C2- Also, you don't really need a drill.=C2- You can hand twi
st them, because they don't have to be tightly wound.
The trick to a well designed, highly reliable system is to run as many sign
als as possible using twisted wire pairs.=C2- This minimizes offenders th
at may induce voltages in signal wires that aren't twisted (stragglers).=C2
- Even power wires to black boxes should be twisted, because power surges
can also create magnetic fields.
Henador Titzoff
On Wednesday, August 28, 2019, 03:39:55 PM EDT, Robert L. Nuckolls, III
<nuckolls.bob@aeroelectric.com> wrote:
>This is not quite true, Bob.=C2- There are several examples oftwisted wi
re cables that do not have shields.=C2- The most ubiquitousexample is Eth
ernet, also >known as 10BASE-T, 100BASE-T and1000BASE-T.
=C2-=C2- But where would we find Cat5 cable
=C2-=C2- on an airplane? I was speaking of wire
=C2-=C2- I might pull from inventory at Beech . . .
=C2- Bob . . .
Message 12
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| Subject: | Re: ARINC Wiring Shield? |
At 03:15 PM 8/28/2019, you wrote:
>
>Well, my Dynon Skyview screens use Cat5 wire between the 2 screens
>to sync data updates and common data like altimeter setting, etc.
>Not required but eases syncing of things. Otherwise, no, I don't
>think of any uses for ethernet cabling in aircraft.
. . . but of course. I've seen some
products exploit the value of crimp
on RJ series connectors. I've got
some transceivers that have RJ45
connectors on the microphone.
The logical extension of using
those connectors is to exploit the
constellation of off-the-shelf
connectors, wire and tooling.
Bob . . .
Message 13
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| Subject: | Re: Wires that pass near a Magnetometer |
At 05:53 PM 8/28/2019, you wrote:
>
>The Whelen product is called Orion 600. Model number is
>OR6001. The light has a pig tail on it, no other wiring. Here is a
>link to the installation guide.
>https://www.whelen.com/install/146/14662.pdf
>
>--------
>Brooks Cone
>Bearhawk Patrol Kit Build
Okay, go talk to this guy
on eBay . . . he has just
what you need
https://tinyurl.com/y6ounn6l
Extend all 4 wires into the cockpit
grounding NOTHING at the wing tip.
Ground the shield at the firewall.
Bob . . .
Message 14
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| Subject: | Z-13/8 review request |
Hello everyone, first time poster here. I would love it if you guys would review
my Z-13/8. Thanks in advance!
This diagram is Bob's Z-13/8 with VERY FEW modifications. I'll point them out
in the pics below.
First here are the pics, sorry they are so big but I'm thinking this is the only
way you will be able to read anything.
I am aware of how to size wires per AC 43.13. However, I went with what the manufacturer
recommended instead
(which was always bigger than AC43.13 or right on). This is why I have at times
two different gauges for the same circuit size.
Yes I know in most instances I can use 22 awg where I speced 20 awg. I already
have plenty of both sizes so no worry there.
Would you all mind taking some time to look it over for any blatant errors? Mega
thank you for taking the time.
First up is the top of the diagram where the backup B&C SD-8 is.
The changes here are the shunt and ANL positions. I have already
installed two ANL fuses on my firewall as I would prefer both battery
and alternator lines be protected. Many find it unnecessary which may
be the case but it's already done and installed. I have also removed the
shunt for the backup alternator because if I am ever running on it I will
know my e-bus is sized right for the current and I can simply monitor bus
voltage. If you REALLY think I need a shunt give me a good reason and I
may install one but at this time I don't see the point.
(https://flic.kr/p/2h6xoGh)1 (https://flic.kr/p/2h6xoGh) by Jereme Carne (https://www.flickr.com/photos/151084592@N02/), on Flickr
Next up is the lower meatier part of the diagram. I eliminated the electronic
ignition and put in for mags instead. I know many like having a dedicated
start button but I really like the left mag also being your start switch. This
method
is also wired such that the right mag must be off to send power to the starter.
As far as
mag switches and the batt/alt switch they are locking toggles. The mags lock in
off and
on with momentary up. The batt/alt switch locks in all three positions. All switches
are
Honeywell TL series. You will also notice that I changed to a B&C main 60amp
alternator and eliminated the low voltage lamp since Dynon will do this on
its own. Also, the battery bus only has a cigarette USB plug and a dome
light on it. Finally, Bob shows a 20awg wire feeding the E-bus from the main
bus which seemed quite small to me. I up sized it to 14awg.
(https://flic.kr/p/2h6zWqs)2 (https://flic.kr/p/2h6zWqs) by Jereme Carne (https://www.flickr.com/photos/151084592@N02/), on Flickr
On to the buses. Here is the main bus. I also tried to include any future
provisions such as the second EFIS even though I don't currently plan it.
The IFD-440 however is in the plan and I'm installing a tray for it now. You
will also notice the amp numbers on the right side of the description. This is
what I could find for MAXIMUM current draw on the device.
(https://flic.kr/p/2h6zeK3)main (https://flic.kr/p/2h6zeK3) by Jereme Carne (https://www.flickr.com/photos/151084592@N02/), on Flickr
Now the E-bus. I really tried to minimize what I put on this to the essentials
but really the end goal was to keep it below 7 ish amps
(which is why the xsponder is still there) So far the MAXIMUM current amounts
add up to 7.35 amps not including the contactor
which is fairly low. (the master at this point would be off so don't worry about
that 1 amp) At 2500 engine RPM by the B&C numbers
you should get about 7.6 amps. It's also worth noting that in my emergency checklist
for this situation I would
unplug/turn off everything on the battery bus.
(https://flic.kr/p/2h6zeLf)ebus (https://flic.kr/p/2h6zeLf) by Jereme Carne (https://www.flickr.com/photos/151084592@N02/), on Flickr
I also am posting the picture of my panel layout if that helps anyone.
(https://flic.kr/p/2gV4VSZ)FINAL PANEL (https://flic.kr/p/2gV4VSZ) by Jereme Carne (https://www.flickr.com/photos/151084592@N02/), on Flickr
I posted this on another forum first and someone brought up two questions which
could probably be answered here.
1. The e-bus is being fed with 2 15 amp fuses (one on the bat bus and one on the
e-bus). Is this a mistake?
2. Can someone explain why there is a fusible link and a CB on the alt field circuit?
Seriously thanks to everyone who helps me look over this big part of my project.
As always if you have questions or comments I welcome it all! :D
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=491111#491111
Message 15
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| Subject: | Re: Z-13/8 review request |
On 8/28/2019 10:22 PM, jcarne wrote:
>
> Hello everyone, first time poster here. I would love it if you guys would review
my Z-13/8. Thanks in advance!
>
> This diagram is Bob's Z-13/8 with VERY FEW modifications. I'll point them out
in the pics below.
>
> First here are the pics, sorry they are so big but I'm thinking this is the only
way you will be able to read anything.
>
> I am aware of how to size wires per AC 43.13. However, I went with what the
manufacturer recommended instead
> (which was always bigger than AC43.13 or right on). This is why I have at times
two different gauges for the same circuit size.
> Yes I know in most instances I can use 22 awg where I speced 20 awg. I already
have plenty of both sizes so no worry there.
>
> Would you all mind taking some time to look it over for any blatant errors?
Mega thank you for taking the time.
>
> First up is the top of the diagram where the backup B&C SD-8 is.
> The changes here are the shunt and ANL positions. I have already
> installed two ANL fuses on my firewall as I would prefer both battery
> and alternator lines be protected. Many find it unnecessary which may
> be the case but it's already done and installed. I have also removed the
> shunt for the backup alternator because if I am ever running on it I will
> know my e-bus is sized right for the current and I can simply monitor bus
> voltage. If you REALLY think I need a shunt give me a good reason and I
> may install one but at this time I don't see the point.
>
> (https://flic.kr/p/2h6xoGh)1 (https://flic.kr/p/2h6xoGh) by Jereme Carne (https://www.flickr.com/photos/151084592@N02/), on Flickr
>
> Next up is the lower meatier part of the diagram. I eliminated the electronic
> ignition and put in for mags instead. I know many like having a dedicated
> start button but I really like the left mag also being your start switch. This
method
> is also wired such that the right mag must be off to send power to the starter.
As far as
> mag switches and the batt/alt switch they are locking toggles. The mags lock
in off and
> on with momentary up. The batt/alt switch locks in all three positions. All
switches are
> Honeywell TL series. You will also notice that I changed to a B&C main 60amp
> alternator and eliminated the low voltage lamp since Dynon will do this on
> its own. Also, the battery bus only has a cigarette USB plug and a dome
> light on it. Finally, Bob shows a 20awg wire feeding the E-bus from the main
> bus which seemed quite small to me. I up sized it to 14awg.
>
> (https://flic.kr/p/2h6zWqs)2 (https://flic.kr/p/2h6zWqs) by Jereme Carne (https://www.flickr.com/photos/151084592@N02/), on Flickr
>
> On to the buses. Here is the main bus. I also tried to include any future
> provisions such as the second EFIS even though I don't currently plan it.
> The IFD-440 however is in the plan and I'm installing a tray for it now. You
> will also notice the amp numbers on the right side of the description. This
is
> what I could find for MAXIMUM current draw on the device.
>
> (https://flic.kr/p/2h6zeK3)main (https://flic.kr/p/2h6zeK3) by Jereme Carne (https://www.flickr.com/photos/151084592@N02/), on Flickr
>
> Now the E-bus. I really tried to minimize what I put on this to the essentials
but really the end goal was to keep it below 7 ish amps
> (which is why the xsponder is still there) So far the MAXIMUM current amounts
add up to 7.35 amps not including the contactor
> which is fairly low. (the master at this point would be off so don't worry about
that 1 amp) At 2500 engine RPM by the B&C numbers
> you should get about 7.6 amps. It's also worth noting that in my emergency checklist
for this situation I would
> unplug/turn off everything on the battery bus.
>
> (https://flic.kr/p/2h6zeLf)ebus (https://flic.kr/p/2h6zeLf) by Jereme Carne (https://www.flickr.com/photos/151084592@N02/), on Flickr
>
> I also am posting the picture of my panel layout if that helps anyone.
>
> (https://flic.kr/p/2gV4VSZ)FINAL PANEL (https://flic.kr/p/2gV4VSZ) by Jereme Carne (https://www.flickr.com/photos/151084592@N02/), on Flickr
>
>
> I posted this on another forum first and someone brought up two questions which
could probably be answered here.
>
> 1. The e-bus is being fed with 2 15 amp fuses (one on the bat bus and one on
the e-bus). Is this a mistake?
> 2. Can someone explain why there is a fusible link and a CB on the alt field
circuit?
>
> Seriously thanks to everyone who helps me look over this big part of my project.
As always if you have questions or comments I welcome it all! :D
>
Quickie on the field circuit: The link protects the wire between the bus
to the breaker; otherwise a short in that wire would see the full fury
of available current on the bus. The CB is there so the overvoltage
module can trip it, opening the field circuit, if there's an overvoltage
fault in the regulator. The field circuit is one of the few circuits
where you might get a 'false positive' due to a short term transient, so
a single reset of the protection device could be warranted.
Philosophy (at least for most of us on this forum) is that virtually all
other activations of circuit protection should be analyzed on the
ground. Any item that's flight-critical should have a backup, meaning
that troubleshooting (circuit resetting) in flight is unnecessary.
Haven't looked closely at your ebus circuit yet, but a 15A fuse is not
terribly robust, so a fault on the bus could conceivably blow both fuses
at once. Not saying to fuse bigger than the wire can stand, but you
might consider bigger feed wires and/or use circuit protection that has
a much longer time constant than a fuse (ANL type device, or my
preference: fusible link).
Welcome aboard!
Charlie
(like I promised...)
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