Today's Message Index:
----------------------
1. 05:11 AM - Bus Bar Equivalent AWG (Drum)
2. 05:35 AM - Re: Bus Bar Equivalent AWG (Art Zemon)
3. 06:25 AM - Re: Bus Bar Equivalent AWG (Charlie England)
4. 07:07 AM - Re: Bus Bar Equivalent AWG (Art Zemon)
5. 07:39 AM - Re: Bus Bar Equivalent AWG (Robert L. Nuckolls, III)
6. 08:12 AM - Re: Bus Bar Equivalent AWG (Charlie England)
7. 11:28 AM - Hall Effect current sensor and Rotax Alternator (Chris)
8. 11:58 AM - Re: Hall Effect current sensor and Rotax Alternator (Robert L. Nuckolls, III)
9. 06:05 PM - Re: Hall Effect current sensor and Rotax Alternator (Robert L. Nuckolls, III)
10. 06:49 PM - Re: Bus Bar Equivalent AWG (Dick Tasker)
11. 07:24 PM - Re: Hall Effect current sensor and Rotax Alternator (user9253)
Message 1
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| Subject: | Bus Bar Equivalent AWG |
Hi - I'm putting together a ground pwr jack for my RV-8. It's easier for me to
connect two contactors using bus bar stock instead of AWG 4 wire. Would 0.5"x.025
brass bus bar stock on a 6' run be acceptable? Can't find a table of brass
bus bar loading data.
Thanks in advance.
Warm regards,
Drum
--------
Drum
RV8 - Working on Fuselage/Canopy
Southport, CT
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=497139#497139
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| Subject: | Re: Bus Bar Equivalent AWG |
Drum,
This would be a good time to think about how you are going to use your
ground power jack, because that will inform how much current needs to flow
through the jack, for how long, and will let you calculate the heat which
would be generated. For instance, if you intend to use the jack to power
the EFIS while you program it, update the database, etc, then the current
is negligible. If you are going to hook up a battery maintainer, again, the
current is negligible. If you are going to use it to jump start the
airplane with a dead battery then you need to shove a lot of current, which
warrants a fat wire or bus bar, but maybe removing the battery and charging
it and then reinstalling it would be preferable. Even in this case, you
have a lot of current but (hopefully) for a short time so not much heat.
-- Art Z.
On Thu, Jul 2, 2020 at 7:23 AM Drum <dgrinalds@gmail.com> wrote:
>
> Hi - I'm putting together a ground pwr jack for my RV-8. It's easier for
> me to connect two contactors using bus bar stock instead of AWG 4 wire.
> Would 0.5"x.025 brass bus bar stock on a 6' run be acceptable? Can't find
> a table of brass bus bar loading data.
>
--
https://CheerfulCurmudgeon.com/
*If I am not for myself, who will be for me? If I am only for myself, what
am I? If not now, when?*
Message 3
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| Subject: | Re: Bus Bar Equivalent AWG |
Art makes a good point.
But directly to your question, #4 wire area is 0.03268...sq in. .5 x .025
0.0125 sq in. Brass conductivity is quite a bit worse than copper. So you'd
have roughly 1/3 the area, and brass has 28% of the conductivity of copper,
if the area was the same.
https://www.bluesea.com/resources/108/Electrical_Conductivity_of_Materials#:~:text=Brass%20is%20only%2028%25%20as,7%25%20as%20conductive%20as%20copper!&text=The%20higher%20the%20%25%20IACS%2C%20the,C%20(68%C2%B0F).
Offsetting that is the very short distance for a bus bar (minimal total
resistance).
However, a thickness of 0.065" would give you the same area, and a piece of
3/8" copper tubing (available at your local hardware store), when
flattened, would give you a 0.54" x 0.095" bar.
Charlie
On Thu, Jul 2, 2020 at 7:40 AM Art Zemon <art@zemon.name> wrote:
> Drum,
>
> This would be a good time to think about how you are going to use your
> ground power jack, because that will inform how much current needs to flow
> through the jack, for how long, and will let you calculate the heat which
> would be generated. For instance, if you intend to use the jack to power
> the EFIS while you program it, update the database, etc, then the current
> is negligible. If you are going to hook up a battery maintainer, again, the
> current is negligible. If you are going to use it to jump start the
> airplane with a dead battery then you need to shove a lot of current, which
> warrants a fat wire or bus bar, but maybe removing the battery and charging
> it and then reinstalling it would be preferable. Even in this case, you
> have a lot of current but (hopefully) for a short time so not much heat.
>
> -- Art Z.
>
> On Thu, Jul 2, 2020 at 7:23 AM Drum <dgrinalds@gmail.com> wrote:
>
>>
>> Hi - I'm putting together a ground pwr jack for my RV-8. It's easier for
>> me to connect two contactors using bus bar stock instead of AWG 4 wire.
>> Would 0.5"x.025 brass bus bar stock on a 6' run be acceptable? Can't find
>> a table of brass bus bar loading data.
>>
>
> --
> https://CheerfulCurmudgeon.com/
> *If I am not for myself, who will be for me? If I am only for myself, what
> am I? If not now, when?*
>
Message 4
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| Subject: | Re: Bus Bar Equivalent AWG |
There are a couple more offsetting features of the bus bar. First, it is
mounted away from everything else, so that air can circulate freely around
it, helping dissipate heat. Second, it is an uninsulated piece of metal. It
can get hot without damaging anything, in particular, it can get hot
without melting insulation.
This is kind of a fun thought experiment but, unless you are going to crank
and crank and crank your engine through that ground power jack and a set of
jumper cables, I kind of doubt that the choice of a bus bar vs a #4 cable
or even vs a piece of AWG 18 wire will make any practical difference.
-- Art Z.
On Thu, Jul 2, 2020 at 8:42 AM Charlie England <ceengland7@gmail.com> wrote:
> Art makes a good point.
> But directly to your question, #4 wire area is 0.03268...sq in. .5 x .025
> 0.0125 sq in. Brass conductivity is quite a bit worse than copper. So you'd
> have roughly 1/3 the area, and brass has 28% of the conductivity of copper,
> if the area was the same.
>
> https://www.bluesea.com/resources/108/Electrical_Conductivity_of_Materials#:~:text=Brass%20is%20only%2028%25%20as,7%25%20as%20conductive%20as%20copper!&text=The%20higher%20the%20%25%20IACS%2C%20the,C%20(68%C2%B0F).
>
> Offsetting that is the very short distance for a bus bar (minimal total
> resistance).
>
> However, a thickness of 0.065" would give you the same area, and a piece
> of 3/8" copper tubing (available at your local hardware store), when
> flattened, would give you a 0.54" x 0.095" bar.
>
> Charlie
>
> On Thu, Jul 2, 2020 at 7:40 AM Art Zemon <art@zemon.name> wrote:
>
>> Drum,
>>
>> This would be a good time to think about how you are going to use your
>> ground power jack, because that will inform how much current needs to flow
>> through the jack, for how long, and will let you calculate the heat which
>> would be generated. For instance, if you intend to use the jack to power
>> the EFIS while you program it, update the database, etc, then the current
>> is negligible. If you are going to hook up a battery maintainer, again, the
>> current is negligible. If you are going to use it to jump start the
>> airplane with a dead battery then you need to shove a lot of current, which
>> warrants a fat wire or bus bar, but maybe removing the battery and charging
>> it and then reinstalling it would be preferable. Even in this case, you
>> have a lot of current but (hopefully) for a short time so not much heat.
>>
>> -- Art Z.
>>
>> On Thu, Jul 2, 2020 at 7:23 AM Drum <dgrinalds@gmail.com> wrote:
>>
>>>
>>> Hi - I'm putting together a ground pwr jack for my RV-8. It's easier
>>> for me to connect two contactors using bus bar stock instead of AWG 4
>>> wire. Would 0.5"x.025 brass bus bar stock on a 6' run be acceptable?
>>> Can't find a table of brass bus bar loading data.
>>>
>>
>> --
>> https://CheerfulCurmudgeon.com/
>> *If I am not for myself, who will be for me? If I am only for myself,
>> what am I? If not now, when?*
>>
>
--
https://CheerfulCurmudgeon.com/
*If I am not for myself, who will be for me? If I am only for myself, what
am I? If not now, when?*
Message 5
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| Subject: | Re: Bus Bar Equivalent AWG |
>However, a thickness of 0.065" would give you the same area, and a
>piece of 3/8" copper tubing (available at your local hardware
>store), when flattened, would give you a 0.54" x 0.095" bar.
Art and Charlie make excellent points. Another
possibility is to fabricate a 4AWG welding
cable jumper that's a 'bit too long' so that
it simply makes a graceful curve between the
studs.
The copper tube idea has been floated and
incorporated in projects here on the list
for decades. Copper is the bus bar material
of choice and you only need to flatten the ends
to facilitate joining at the studs. This
technique calls for attention to keeping
the two flats planar to each other.
My personal choice would be the welding
cable jumper. Easy to build, soft and
easy to work with. Does not conduct
mechanical forces between the studs.
I'm recalling an invitation I received from
an RV builder in Wichita to visit his project
in process on local airport. We had some
good discussion about various chapters of
his planning. While looking over stuff fire-wall-
forward, I noticed that he had grounded battery(-)
to the fire-wall sheet with a little chunk of aluminum
angle.
I brought this to his attention and suggested
that the thin stainless was a poor conductor
and that forcing it to carry battery recharge
and starter cranking currents offer potential
for serious ground-loop effects. But more important,
the battery mass was getting tied to airframe
by non-structural battery terminal by way
of a non-ferrous hunk of metal that was almost
guaranteed to be his first electrical system
failure.
I think he was rather fond of his short-n-
simple grounding idea . . . he got a bit incensed
but it was about time for me to depart anyhow.
Never did hear any follow-up on the project.
But it's an experience that reminds me to
ponder system rigidity between significant
chunks of hardware when making hard connection
to studs designed for terminating relatively
soft wires.
Bob . . .
Message 6
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| Subject: | Re: Bus Bar Equivalent AWG |
On 7/2/2020 9:37 AM, Robert L. Nuckolls, III wrote:
>> However, a thickness of 0.065" would give you the same area, and a
>> piece of 3/8" copper tubing (available at your local hardware store),
>> when flattened, would give you a 0.54" x 0.095" bar.
>
> Art and Charlie make excellent points. Another
> possibility is to fabricate a 4AWG welding
> cable jumper that's a 'bit too long' so that
> it simply makes a graceful curve between the
> studs.
>
> The copper tube idea has been floated and
> incorporated in projects here on the list
> for decades. Copper is the bus bar material
> of choice and you only need to flatten the ends
> to facilitate joining at the studs. This
> technique calls for attention to keeping
> the two flats planar to each other.
>
> My personal choice would be the welding
> cable jumper. Easy to build, soft and
> easy to work with. Does not conduct
> mechanical forces between the studs.
>
> I'm recalling an invitation I received from
> an RV builder in Wichita to visit his project
> in process on local airport. We had some
> good discussion about various chapters of
> his planning. While looking over stuff fire-wall-
> forward, I noticed that he had grounded battery(-)
> to the fire-wall sheet with a little chunk of aluminum
> angle.
>
> I brought this to his attention and suggested
> that the thin stainless was a poor conductor
> and that forcing it to carry battery recharge
> and starter cranking currents offer potential
> for serious ground-loop effects. But more important,
> the battery mass was getting tied to airframe
> by non-structural battery terminal by way
> of a non-ferrous hunk of metal that was almost
> guaranteed to be his first electrical system
> failure.
>
> I think he was rather fond of his short-n-
> simple grounding idea . . . he got a bit incensed
> but it was about time for me to depart anyhow.
> Never did hear any follow-up on the project.
> But it's an experience that reminds me to
> ponder system rigidity between significant
> chunks of hardware when making hard connection
> to studs designed for terminating relatively
> soft wires.
>
> Bob . . .
>
I do try to put some variation of an 'S' curve in the flattened copper
tubing, when I use that trick. Helps relieve flex stress in one
direction, anyway...
Charlie
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Message 7
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| Subject: | Hall Effect current sensor and Rotax Alternator |
I was wondering what locations might be possible for installing a hall
effect current sensor on a Z-16 system. Will one or both yellow wires work??
Or, am I limited to the battery lead?
Thanks
Chris
Just Highlander
Message 8
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| Subject: | Re: Hall Effect current sensor and Rotax Alternator |
At 01:22 PM 7/2/2020, you wrote:
>I was wondering what locations might be possible for installing a
>hall effect current sensor on a Z-16 system. Will one or both yellow
>wires work?? Or, am I limited to the battery lead?
>Thanks
>Chris
>Just Highlander
the yellow wires carry AC current at values
related to but different from the DC output
of the rectifier regulator. If you're wishing to
incorporate the legacy DC hall sensor common to
virtually all EFIS systems, the sensor goes in
the BAT leads of the rectifier regulator.
Bob . . .
Message 9
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| Subject: | Re: Hall Effect current sensor and Rotax Alternator |
At 01:22 PM 7/2/2020, you wrote:
>I was wondering what locations might be possible for installing a
>hall effect current sensor on a Z-16 system. Will one or both yellow
>wires work?? Or, am I limited to the battery lead?
>Thanks
>Chris
>Just Highlander
See attached
Bob . . .
Message 10
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| Subject: | Re: Bus Bar Equivalent AWG |
Do you really mean 6 ft.? Or is it a typo (6') and should have been 6"?
Dick Tasker
Drum wrote:
>
> Hi - I'm putting together a ground pwr jack for my RV-8. It's easier for me
to connect two contactors using bus bar stock instead of AWG 4 wire. Would 0.5"x.025
brass bus bar stock on a 6' run be acceptable? Can't find a table of
brass bus bar loading data.
>
> Thanks in advance.
>
> Warm regards,
>
> Drum
>
> --------
> Drum
> RV8 - Working on Fuselage/Canopy
> Southport, CT
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=497139#497139
>
>
Message 11
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| Subject: | Re: Hall Effect current sensor and Rotax Alternator |
The yellow wires carry AC current from the Rotax dynamo
Run the B & R direct current wires from the Ducati regulator through the hall effect
sensor.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=497153#497153
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