Today's Message Index:
----------------------
1. 05:55 AM - Re: Alternator capacity (Robert L. Nuckolls, III)
2. 06:29 AM - Re: Need 1,2 & 3 amp fuses (Robert L. Nuckolls, III)
3. 09:28 AM - Still "fighting" with Audio Ground (Carlos Trigo)
4. 10:10 AM - Re: Still "fighting" with Audio Ground (Robert L. Nuckolls, III)
5. 10:51 AM - Wire deals on ebay . . . (Robert L. Nuckolls, III)
6. 12:28 PM - Re: Need 1,2 & 3 amp fuses (Ernest Christley)
7. 01:03 PM - Re: Re: Sub Panel Labeling (Henry Trzeciakowski)
Message 1
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| Subject: | Re: Alternator capacity |
At 06:07 AM 11/8/2008 -0800, you wrote:
><Tom@CostanzaAndAssociates.com>
>
>Hi all,
>
>What should I consider when I calculate the capacity of an
>alternator? I've read Bob's posts about never seeing a situation that
>couldn't be served by a 40A unit. But if I just add the requirements of
>each item, I get closer to 60A. Should I consider things like
>landing/taxi lights (I have 4 bulbs @ 6.5A each), or count them as zero
>(since they will only be used for a few minutes before, during, and after
>landing)? What else am I missing?
If you used landing and taxi lights intermittently
and for short periods of time, they do not become
high-energy loads that beg for continuous support
by the alternator. Do you use all four lights on
at any one time?
On my website at:
http://www.aeroelectric.com/PPS/Load_Analysis/
you will find a number of exemplar spread
sheets where members have conducted their
own detailed load analysis. You can take
one of these and consider it for how changes
to match your airplane would give you a clearer
picture of your operational energy requirements.
There is also a blank form at:
http://www.aeroelectric.com/PPS/Load_Analysis/Blank_Form.pdf
I use this format as the index page to my
wire-book products where the load analysis
becomes a list of all electrical sub-systems
in the airplane, indexes the page were wiring
for that sub-system can be found in the wire-book,
and discusses energy requirements for each
sub-system depending on how and when it is
used in the operation of the airplane. An
exemplar work-in-progress can be seen here:
http://www.aeroelectric.com/Reference_Docs/Misc_PDF/N820JPWB.pdf
Depending on how and in what combinations you
operate appliances in your aircraft, you may well
find that a 40A alternator has the necessary
overhead to run all needed equipment while holding
10A or so in reserve for the purpose of recharging
a battery.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 2
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| Subject: | Re: Need 1,2 & 3 amp fuses |
It seems worth mentioning that in the situations mentioned & others like
them, the manufacturer is saving himself the expense of building protection
into his device and shifting responsibility for protection to the
installer. Now, if something burns, he can blame *you* instead of accepting
responsibility for his design.
That's a pretty broad brush my friend. Where is it
written that the installer should not have to consider
design limitations for an appliance's integration
into the system? Is it not a good idea to put say
40A of protection on a 20A landing gear pump with
the notion that a stalled motor will pop the breaker
as opposed to burning wires in the motor? Should I
decide to hang hang the 20A motor on a feeder
protected at 100 amps, is it reasonable to demand
or expect the motor supplier to include optimized
protection inside the motor?
While it is not the duty of the system integrator
to discover and make adjustments for limitations
imposed by a product's design, it IS A DUTY
of designers to make those limitations known
before the customer buys the product.
Example. See . . .
http://www.aeroelectric.com/Catalog/AEC/9011/9011-700-1C.pdf
I've called out 2A fuses that will open before
traces internal to my product will burn. The risks
for raising those to 5A are not great . . . but should
I get one back for repairs and have to deal with
a burned trace, am I ethically bound to "eat" those
costs of repair because my design does not incorporate
protection suited to 5A feeders (or Richter's 10A
feeders)?
That way, there are no surprises in what should be
an honorable free-market exchange of value. The
buyer has the option of deciding whether or not
he will go to the effort to supply a 2A fuse
before he buys my product. I've designed many
products where there were fusible components
within that prevented component failures
from escalating repair costs. In this case it
was attractive to use 2A protection OUTSIDE as
opposed to INSIDE the box. I'll suggest there is
no dishonor in expecting a customer to comply
with installation recommendations as long as I make
him aware of it before he hands me money and I
hand him hardware.
Bob . . .
Message 3
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| Subject: | Still "fighting" with Audio Ground |
One has to be very careful with Audio grounds, to avoid unwanted "noise",
and I'm still "fighting" with this.
I am finishing my Intercom wiring and I have what I think to be my last
question about this subject:
I have to connect 3 shielded wires (Radio Receive Audio, Radio Transmit
Audio and Nav Audio) from the SL-30 Comm/Nav Radio to the Intercom, and I
wonder if I should connect the shields to audio ground on both ends (Radio
and Intercom) or only one side (which one?)?
Carlos
Message 4
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| Subject: | Re: Still "fighting" with Audio Ground |
At 05:26 PM 11/9/2008 +0000, you wrote:
>One has to be very careful with Audio grounds, to avoid unwanted noise ,
>and I m still fighting with this.
>
>I am finishing my Intercom wiring and I have what I think to be my last
>question about this subject:
>
>
>I have to connect 3 shielded wires (Radio Receive Audio, Radio Transmit
>Audio and Nav Audio) from the SL-30 Comm/Nav Radio to the Intercom, and I
>wonder if I should connect the shields to audio ground on both ends (Radio
>and Intercom) or only one side (which one?)?
What do the installation instructions show?
See page 13 of . . .
http://www.aeroelectric.com/DIY/Audio_Isolation_Amplifier.pdf
Here I show a combination of shielded wires where
some instances use the shield for both noise
mitigation -AND- part of a signal pathway . . .
i.e. shields connected at both ends. In others
the are not used to serve any purpose other than
noise mitigation.
Make sure that your installation instructions
do not show specific connections to both ends.
If not, ground once to either end. It doesn't
matter which on a small installation like the
panel of an S.E. aircraft.
Bob . . .
Message 5
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| Subject: | Wire deals on ebay . . . |
This guy has a couple 1000 foot spools of 22AWG
wire for a good price.
http://shop.ebay.com/merchant/deagle1969
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 6
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| Subject: | Re: Need 1,2 & 3 amp fuses |
Carlos Trigo wrote:
> Bill
>
>
>
> I am not an EE, as a matter of fact I'm a Civil Eng, but it seems to me that
> although fuses are designed to protect the wire, the current (which
> determines the fuse Amp) that runs through the wire depends on the device it
> serves.
>
> For example, when installing the GPSx96 in the panel the instructions call
> for a 1A fuse or CB, and the AOA Cpu from Proprietary (now AFS) calls for
> 4A, and Flightcom 403 intercom call for AWG 20 or 22 wire and 1A
> breaker/fuse.
>
>
>
> Am I missing something?
>
>
Not really.
The device needs a certain amount of current. This sets the lower limit
of what size fuse you can use. You can use a smaller fuse, but it's not
much fun swapping blown fuses.
The wire can only carry a certain amount of current, determined by its
diameter and length. This sets the upper size of fuse that you can
safely use. You can use a larger fuse, but then you're really making
your wire the fuse.
Between those limits is the headroom you have for making fuse rating
choices.
Choose to the low side if the device has a stable current draw, and you
think a blown fuse might actually do something to save the device.
Motors and lamps have high inrush currents, so aren't stable loads. A
fuse might do something to save a stalled motor, but it isn't going to
do anything to save a lamp.
Choose to the high side for loads with high momentary currents, and
loads that you willing to let sacrifice themselves for your safety or
comfort.
--
http://www.ernest.isa-geek.org
Message 7
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| Subject: | Re: Sub Panel Labeling |
Bill
I don't see your attachments?
Thanks
henry
----- Original Message -----
From: <Flagstone@cox.net>
Sent: Saturday, November 01, 2008 12:52 PM
Subject: Re: AeroElectric-List: Re: Sub Panel Labeling
>
> Bill:
>
> Would you mind posting details of how you made your labels.
>
> Thanks
> ----- Original Message -----
> From: "William Gill" <wgill10@comcast.net>
> To: <aeroelectric-list@matronics.com>
> Sent: Thursday, October 30, 2008 6:59 PM
> Subject: RE: AeroElectric-List: Re: Sub Panel Labeling
>
>
> > Henry,
> >
> > Attached are a few examples from my project.
> >
> > Bill
> > RV-7 N151WP
> >
> > -----Original Message-----
> > From: owner-aeroelectric-list-server@matronics.com
> > [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Henry
> > Trzeciakowski
> > Sent: Thursday, October 30, 2008 8:42 PM
> > To: aeroelectric-list@matronics.com
> > Subject: AeroElectric-List: Re: Sub Panel Labeling
> >
> > Gentlemen:
> >
> > I've seen numerous e-mails, etc regarding panel labeling, but I really
> > didn't see comments regarding the "COLOR" of the lettering. I've
> > researched
> > thru various FAA sites, etc., and I couldn't find articles as to what
> > the
> > "Legal" color for lettering should be (black, white).
> >
> > I have a meduim Gray Panel (see attachment) and I'm leaning towards
> > BLACK
> > Lettering...it stands out better.
> >
> > I woud appreciate any feedback or suggestions.
> >
> >
> >
> > Henry
> > Pittsburgh, Pa.
> > RV-9A - wiring started
> >
>
>
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