Today's Message Index:
----------------------
1. 01:08 AM - Re: Re: Battery Bus Location (Jay Hyde)
2. 03:03 AM - Re: Re: [AeroElectric-List] Questions about circuit protection (Jay Hyde)
3. 04:25 AM - Re: Re: Question about 16V POLYFUSER Radial Leaded Resettable PTC (Neal George)
4. 06:09 AM - Re: Re: [AeroElectric-List] Questions about circuit protection (ROGER & JEAN CURTIS)
5. 07:09 AM - Re: Re: [AeroElectric-List] Questions about circuit protection (Carlos Trigo)
6. 07:25 AM - Re: Question about 16V POLYFUSER Radial Leaded Resettable PTC (al38kit)
7. 08:02 AM - Re: Battery Bus Location (PaulR)
8. 08:03 AM - Re: Re: Question about 16V POLYFUSER Radial Leaded Resettable PTC (Dennis Golden)
9. 08:03 AM - Re: Re: [AeroElectric-List] Questions about circuit protection (Dan Brown)
10. 08:24 AM - Re: Z-14 Switch Combos (Perry, Phil)
11. 08:33 AM - Re: Z-14 Switch Combos (Robert L. Nuckolls, III)
12. 08:56 AM - Re: Re: [AeroElectric-List] Questions about circuit protection (Robert L. Nuckolls, III)
13. 09:15 AM - Re: Re: Battery Bus Location (Robert L. Nuckolls, III)
14. 09:31 AM - Re: Re: Battery Bus Location (Robert L. Nuckolls, III)
15. 09:35 AM - Re: Tachometer problems (Robert L. Nuckolls, III)
16. 09:41 AM - Re: Re: Question about 16V POLYFUSER Radial Leaded Resettable PTC (Robert L. Nuckolls, III)
17. 09:47 AM - Re: AeroElectric-List Digest: 16 Msgs - 01/05/10 (Jesse Jenks)
18. 09:54 AM - Re: [AeroElectric-List] Questions about circuit protection (Carlos Trigo)
19. 09:54 AM - Re: Re: Question about 16V POLYFUSER Radial Leaded Resettable PTC (George, Neal E Capt USAF ACC 505 TRS/DOJ)
20. 10:14 AM - Re: Re: [AeroElectric-List] Questions about circuit protection (Bill Mauledriver Watson)
21. 10:17 AM - Electrical System Planning (Robert L. Nuckolls, III)
22. 10:48 AM - Re: [AeroElectric-List] Questions about circuit protection (Carlos Trigo)
23. 10:57 AM - Re: Re: [AeroElectric-List] Questions about circuit protection (ROGER & JEAN CURTIS)
24. 11:17 AM - Re: Re: [AeroElectric-List] Questions about circuit protection (ROGER & JEAN CURTIS)
25. 11:54 AM - Re: Re: Question about 16V POLYFUSER Radial Leaded Resettable PTC (jerb)
26. 02:06 PM - List decorum (Robert L. Nuckolls, III)
27. 08:07 PM - Re: Z-14 Switch Combos (Perry, Phil)
Message 1
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Subject: | Re: Battery Bus Location |
I put one of my battery busses on the hot side of the firewall and the other
on the cold side (2 batteries). My reasoning was that I would rather have
the connection between the buss and the battery short on the hot side than
lead the wire to the cold side.
For the second battery, which is located in the cargo compartment, I had to
lead a long fat wire to the front, as per my previous mail. The battery bus
is located where the fat wire ends at the firewall, on the contactor for
that battery. As Bob pointed out, this is not ideal as it means that you
have a long fat wire (now protected by an inline fuse as described in my
last mail) between the battery and the contactor. The rational for this is
that the routing between the front and back is not easy and I would rather
have 1 mechanically robust wire than several smaller wires that might be
subject to chaffing and damage- the fat wire is much easier to protect
mechanically. Not ideal, but adapted to the situation that I have...
Jay
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: 06 January 2010 01:30 AM
Subject: Re: AeroElectric-List: Re: Battery Bus Location
<nuckolls.bob@aeroelectric.com>
At 04:10 PM 1/5/2010, you wrote:
>
>Bob,
>Thanks for the reply. I'm not opposed to putting it outside on the
>firewall, I just didn't know whether the fuse blocks from B&C would
>be alright out there. I think you spell out 6" length on the feed wire.
That's an idealized notion. If you need to make it 12"
or even longer to satisfy design goals, the world is
not going to come to an end.
> If I stick to that, which makes sense unprotected, then I would
> have to put it directly on the inside of the firewall which would
> be extremely difficult to get to for service. Hopefully none will
> be required, but it would be easier on the hot side.
Then put it in a location for ease of maintenance.
That would be my choice as well. Think about a
way to at least cover if not box-up the fuseblock
like they do under the hood of cars.
>The insulator would indeed be a good method to get the wire inside,
>but the length is still a factor.
The length isn't a REALLY BIG thing, just a
good practice design rule adopted by the TC
side of the house many years ago. How long would
the wire be for both extending the battery
feeder AND ease of maintenance?
>Does most everyone else put them on the hot side?
Good question. How about it guys? Anyone out
there flying fuse blocks on the forward side
of the firewall?
Bob . . .
Message 2
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Subject: | RE: [AeroElectric-List] Questions about circuit |
protection
I use fuses for my designs as well and add what I call a FAP (Fuse
Annunciator Panel) which is an array of LED's that are connected to the
'downsteam' side of the fuse. By pressing a common pushbutton that connects
all of the LED's to ground I can immediately see whether all of the fuses
are OK. For the pilot this is great- press the button on the pre-flight and
the status of all the fuses is shown; and in flight they can check the fuses
the same way if there is some suspicion that a fuse has blown. It requires
some extra PT with the wiring but I am working on a fuse holder that will
make this much easier. My first version was a bit clumsy, but they're
getting better. I even have a light test button. :-)
Jay
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Jared
Yates
Sent: 06 January 2010 08:16 AM
Subject: RE: AeroElectric-List: RE: [AeroElectric-List] Questions about
circuit protection
In some of the larger factory-made airplanes, the breakers are situated
behind the pilot's head. In this location popped breakers are only obvious
if you get up out of your seat to look. It's pretty embarrassing to call
the maintenance guys, go through some diagnostics on a non-functioning
gadget, then have them instruct you to pull the breaker and doh! It was
popped all along. One time I tried to extend the flaps for landing, but
they didn't extend because all 5 of the flap motor circuit breakers have
been pulled since before takeoff. In that case the mechanics were working
on the flaps, pulled the breakers as a normal safety measure, but then
forgot to put them in when they were done. Then two pilots didn't notice
that they were out, at least not until configuring for the landing. In that
airplane the normal flap setting for takeoff was zero. I can think of
several other similar stories that illustrate that popped breakers aren't
necessarily all that obvious. Once you realize that something isn't working
and start looking for a breaker, they might be more obvious than a fuse,
unless you spend the extra cents on the bling-bling LED fuses.
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Bob
McCallum
Sent: Tuesday, January 05, 2010 11:11 PM
Subject: RE: AeroElectric-List: RE: [AeroElectric-List] Questions about
circuit protection
Carlos;
Different "Bob" here, but I must disagree with your viewpoint. Please see
embedded comments.
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Carlos
Trigo
Sent: Tuesday, January 05, 2010 8:00 PM
Subject: AeroElectric-List: RE: [AeroElectric-List] Questions about circuit
protection
Bob
I really don't want to resuscitate this discussion but, even being aware of
the technical advantages of fuses versus circuit breakers, it is indeed
almost impossible to convince a pilot that a fuse is better than a circuit
breaker.
Why?? Fuse is simpler, less expensive, probably neater, and serves its
intended purpose admirably. I've been a pilot for 35 years, a builder for
only 5 and I much prefer the simplicity and economy of fuses. I consider
myself a pilot first and I don't need convincing, I know fuses are better.
(At least in my own mind they are)
In flight, when a fuse blows, the pilot will hardly notice it, and even if
some device (whose circuit was protected by that fuse) becomes blank, he
will not know if it was the fuse or anything else that caused that device to
die.
And how is that any different than the symptoms presented by a tripped
breaker? The supplied device ceases to function in either case. To the pilot
operating the aircraft there is no difference, he looses the benefit of
whatever widget was supplied power by that circuit.
If a circuit breaker pops out, there is a big probability the pilot will
immediately notice it, How or why will he notice it?? and why does it
matter?? or at least after seeing any device die, he will immediately look
to the circuit breakers heads to look for the one that popped out.
Are you making the assumption that the breakers are somehow readily
available, visible and accessible in flight?? What if the breakers are
neatly hidden away up under the panel, are on a fold down bracket, or in
some other manner not readily apparent to the pilots position or his line of
sight? What if the breaker that faults is one on the battery buss, hidden
away in the tail cone next the battery? How does that present some different
scenario to the pilot than would a fuse??
Being a pilot trained for so many things, he must also know that he shall
not push that particular breaker in, unless he wants to light up the fire
which will burn his own ass.
All the more reason for, and another demonstration of, the superiority of
hidden fuses. (Or hidden breakers for that matter) Removes the temptation
and doesn't require the discipline and willpower "not to reset".
It is probably easy to convince an aircraft builder to prefer fuses, but
since in the OBAM world we are builders AND pilots, circuit breakers are
certainly much more user friendly for the pilot, even knowing that the PILOT
is the most dangerous single-point-of-failure in a flying aircraft
I really fail to see the "user friendly" analogy. The fuses in all the cars
I've owned have been about as "user friendly" as I can imagine, and in some
of my cars I never had occasion to even learn where they were. Can't
remember the last time one ever blew. In the dozen or so types of aircraft
I'm checked out in, I can't remember the last time a fuse blew, or a breaker
tripped either. In a properly designed and functioning car or aircraft, I
wouldn't "expect" the circuit protection devices to be called upon to do
their job for the life of the vehicle, be it airborne or ground based. I
fully agree with the "insurance" provided by their presence, but wouldn't
expect them to be called upon. (If breakers are somehow superior, why do the
millions of cars on the road use fuses?) As Bob explained the main reason
aircraft migrated to expensive breakers was to mitigate the drawbacks of
"old" technology glass cartridge fuses such as loose retaining caps and low
pressure contacts prone to corrosion. We now have modern "blade" fuses
without these shortcomings.
Don't get me wrong, I fully understand and respect your opinion and
viewpoint, I just can't get a grasp on the logic behind it. As one who makes
a living as an engineer, I view simple as better and fuses are simpler and
less expensive than breakers and have much less chance of having something
go wrong with them which makes the pilot side of me much more relaxed and
comfortable with fuses than breakers.
Carlos
Respectfully,
Bob McC
http://www.matronics.com/Navigator?AeroElectric-List
http://forums.matronics.com
http://www.matronics.com/contribution
Message 3
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Subject: | Re: Question about 16V POLYFUSER Radial Leaded |
Resettable PTC
No sir. We put switches on electrical circuits to provide On/Off control of
the load under normal operations. Once an overload condition manifests,
operations are no longer normal. Powering a circuit that you know has
experienced an overload invites smoke, flame and fury in a confined space
with no reasonable exit.
War story follows:
Standing nuclear alert in the missile fields around Cheyenne, WY, our
procedures allowed ONE attempt to reset a tripped circuit breaker, after a
specified cool-down period. Smoke in the capsule is bad, and getting out is
neither easy nor quick.
Neal
I can understand the concern for a circuit resetting itself after the power
is restored...but isn't that a reason we put switches on things?...Like
leave that circuit off if it has a problem...
Sorry, just don't see the design as having much of a downside. If you think
you may accidentally turn the thing back on, put some red tape on the switch
or something...pull the wire.
Al
Message 4
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Subject: | RE: [AeroElectric-List] Questions about circuit |
protection
Bob
I really don't want to resuscitate this discussion but, even being aware
of
the technical advantages of fuses versus circuit breakers, it is indeed
almost impossible to convince a pilot that a fuse is better than a
circuit
breaker.
In flight, when a fuse blows, the pilot will hardly notice it, and even
if
some device (whose circuit was protected by that fuse) becomes blank, he
will not know if it was the fuse or anything else that caused that
device to
die.
If a circuit breaker pops out, there is a big probability the pilot will
immediately notice it, or at least after seeing any device die, he will
immediately look to the circuit breakers heads to look for the one that
popped out.
Being a pilot trained for so many things, he must also know that he
shall
not push that particular breaker in, unless he wants to light up the
fire
which will burn his own ass.
It is probably easy to convince an aircraft builder to prefer fuses, but
since in the OBAM world we are builders AND pilots, circuit breakers are
certainly much more user friendly for the pilot, even knowing that the
PILOT
is the most dangerous single-point-of-failure in a flying aircraft
Carlos
.Two simple examples:
1) You are flying along in your airplane with circuit breakers, the
radio
goes dead, and a breaker button pops out. What do you do? Fly the
airplane!!
2) You are flying along in your airplane with Fuses, the radio goes
dead,
and nothing else happens. What do you do? Fly the airplane!!
When you get on the ground you troubleshoot the problem.
If the added cost for the row of little buttons to pop out, on the dash,
gives you a sense of security, I say GO FOR IT......
rOGER
Message 5
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Subject: | RE: [AeroElectric-List] Questions about circuit |
protection
.Two simple examples:
1) You are flying along in your airplane with circuit breakers, the radio
goes dead, and a breaker button pops out. What do you do? Fly the
airplane, knowing that something happened in the electric circuit that is
protected by that particular circuit breaker. If the radio (or anything else
that went dead) is not critical to your flight, you complete it with no
other worries
2) You are flying along in your airplane with Fuses, the radio goes dead,
and nothing else happens. What do you do? Fly the airplane!! not knowing
what happened. Did I loose the alternator? Is there anything that is going
to start a fire? What should I do? Should I land ASAP? Shall I declare an
emergency? Next, anything can happen to the pilot, even panic
When you get on the ground you troubleshoot the problem. If it was a fuse,
it can take some time to find out which. If it was a circuit breaker, I will
go IMMEDIATELY to the source of the problem
If the added cost for the row of little buttons to pop out, on the dash,
gives you a sense of security, I say GO FOR IT...... I have 1 airplane with
fuses, 1 airplane with cb's, and the one I'm finishing building have both.
Not biased, though. :-) Only analysing pros and cons.
Carlos
Message 6
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Subject: | Re: Question about 16V POLYFUSER Radial Leaded Resettable |
PTC
Neal...having spent some time in the military myself, I know there is ofter not
much thinking that is to be done, and a procedure for almost everything...
That being said and that we are no longer held to that kind of procedure, what's
the down side to leaving the switch off?
No one says you have to reset it.
My understanding is that once the electrons are removed from the circuit, it's
dead.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=280355#280355
Message 7
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Subject: | Re: Battery Bus Location |
[/quote]
The length isn't a REALLY BIG thing, just a
good practice design rule adopted by the TC
side of the house many years ago. How long would
the wire be for both extending the battery
feeder AND ease of maintenance?
I think i could get by with 18-24" depending on how "easily maintainable" it is.
While it's really too cold to heat the shop up for a couple hours, I think I'll
see if I can find a covered fuse block until I'm back in the shop over the weekend
--------
Paul Rose
N417PR (res)
RV-9A
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=280358#280358
Message 8
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Subject: | Re: Question about 16V POLYFUSER Radial Leaded |
Resettable PTC
al38kit wrote:
>
> Neal...having spent some time in the military myself, I know there is ofter not
much thinking that is to be done, and a procedure for almost everything...
>
> That being said and that we are no longer held to that kind of procedure, what's
the down side to leaving the switch off?
>
> No one says you have to reset it.
>
> My understanding is that once the electrons are removed from the circuit, it's
dead.
What if the fault IS the switch, or the wiring going TO the switch.
Dennis
--
Dennis Golden
Golden Consulting Services, Inc.
Message 9
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Subject: | RE: [AeroElectric-List] Questions about circuit |
protection
Quoting Carlos Trigo <trigo@mail.telepac.pt>:
> 2) You are flying along in your airplane with Fuses, the radio goes dead,
> and nothing else happens. What do you do? Fly the airplane!! not knowing
> what happened. Did I loose the alternator? Is there anything that is going
> to start a fire? What should I do? Should I land ASAP? Shall I declare an
> emergency? Next, anything can happen to the pilot, even panic
Losing the alternator won't take out the radio, unless you don't have
a battery (in which case it will take out everything electrical).
Losing the alternator will, however, activate the low-voltage warning
that you have installed (don't you?), letting you know that you're
running on battery power. If you're panicking (as most of your
questions sound like) over losing one radio, you probably shouldn't be
a pilot.
> When you get on the ground you troubleshoot the problem. If it was a fuse,
> it can take some time to find out which.
If it takes you more than 30 seconds to find which fuse goes to that
radio, you haven't designed or labeled your electrical system very well.
--
Dan Brown, KE6MKS, dan@familybrown.org
"Since all the world is but a story, it were well for thee to buy the
more enduring story rather than the story that is less enduring."
-- The Judgment of St. Colum Cille
Message 10
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Subject: | Z-14 Switch Combos |
Hey Bob,
It looks like the crossfeed switch doubles as a starter switch in your
diagram, is that correct?
I'm planning on going with a push button to start, so I'll probably
modify the setup slightly. But just want to make sure I'm reading it
correctly.
Thanks,
Phil
-----Original Message-----
From: Robert L. Nuckolls, III [mailto:nuckolls.bob@aeroelectric.com]
Sent: Tuesday, January 05, 2010 9:29 AM
Subject: RE: AeroElectric-List: Z-14 Switch Combos
<nuckolls.bob@aeroelectric.com>
At 09:08 PM 1/4/2010, you wrote:
>
>Phil -
>
>I think you misinterpreted Bob's comment. It appears you read it to
say
>"you're never ALLOWED to close the cross-feed switch", when Bob meant
"you
>might not ever have a reason to close it".
>
>Neal
Correct. The process for deciding how to operate
Z-14 is dependent upon what devices are
fed from each bus and how you use the airplane.
Z-14 was originally crafted for a guy building
a Glasair with full up IFR capability in both
seats. Further, it was the builder's intent to
use this machine in missions that most of us
work hard to avoid.
Z-14 offers OPTIONS for deciding how you will
manage energy resources that have become limited
due to failure of some component like an alternator
or battery contactor.
There is no SET PROCEDURE I can offer you without
doing the same failure modes effects analysis
I would conduct for a TC aircraft with a similar
system installed and tailored to the most demanding
mission for which the airplane is outfitted.
Z-14's cross-feed contactor solved a problem
with attempting to PARALLEL two alternators
in a dual alternator airplane by making them
responsible for SEPARATE systems in normal
operations.
Z-13/8 was crafted to take exploit the existence
of an unused engine accessory drive pad when
a vacuum pump is removed. Some politicians hate
to waste a good crisis, I had to waste a good
drive pad. When considered against the quantum
jumps in reliability offered by modern alternators
and artfully maintained RG batteries, I believe
Z-13/8 is about the most elegant solution to
powering up the light airplane for 99 plus
percent of all OBAM aircraft.
If you have Z-14 installed, then share with us
how equipment in your airplane is powered from
the two busses along with your vision of how
you expect to use this airplane. Is it important
to you to forestall a dark-n-stormy night story
'cause you've had an alternator go belly up while
night IFR over the Rockies crossing a weather
front? If so, what items of equipment are installed
and how are they spread between the two systems?
Bob . . .
Message 11
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Subject: | Z-14 Switch Combos |
At 10:19 AM 1/6/2010, you wrote:
>
>Hey Bob,
>
>It looks like the crossfeed switch doubles as a starter switch in your
>diagram, is that correct?
Yes . . . it's spring loaded out of the start position.
It offers automatic closure of the cross-feed contactor
during start.
>I'm planning on going with a push button to start, so I'll probably
>modify the setup slightly. But just want to make sure I'm reading it
>correctly.
Then the cross-feed switch can be SPST.
Bob . . .
Message 12
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Subject: | Re: RE: [AeroElectric-List] Questions about circuit |
protection
At 07:00 PM 1/5/2010, you wrote:
>Bob
>
>I really don=92t want to resuscitate this
>discussion but, even being aware of the
>technical advantages of fuses versus circuit
>breakers, it is indeed almost impossible to
>convince a pilot that a fuse is better than a circuit breaker.
It has never been offered as 'better' . . . only
adequate to the task of meeting design goals in
a failure tolerant system.
>In flight, when a fuse blows, the pilot will
>hardly notice it, and even if some device (whose
>circuit was protected by that fuse) becomes
>blank, he will not know if it was the fuse or
>anything else that caused that device to die.
Have you read . . .
http://www.aeroelectric.com/articles/fusvbkr2.html
>If a circuit breaker pops out, there is a big
>probability the pilot will immediately notice
>it, or at least after seeing any device die, he
>will immediately look to the circuit breakers
>heads to look for the one that popped out.
>Being a pilot trained for so many things, he
>must also know that he shall not push that
>particular breaker in, unless he wants to light
>up the fire which will burn his own ass=85
It's not clear that you embrace/understand the
rationale presented for unreachable fuse-blocks.
Certainly everyone has a choice to make and
in the final analysis it's personal. I did a
power distribution diagram for the BD-10 jet
about 15 years ago. I bounced the idea of fuse-blocks
off the electrical systems wienie. He agreed that
they were adequate to the task but opined that
anyone building a BD-10 wanted that "busy fighter
cockpit look. The more knobs, buttons and switches
the better." But even after the drawing was completed
using breakers throughout, he about had a cow when
I put about a dozen breakers back in the engine
compartment. The architecture called for protection
in these feeders and the sources for those feeders
were in the tail. Further, there was no failure
mode effects analysis that supported any need for
pilot access to these breakers whatsoever. Nonetheless,
he insisted on having all breakers in the cockpit.
I submitted my bill for work accomplished to date
and bowed out of the project. Got a nastygram from
Mr. Bede hisself honking about the fee and stating
that his electro-wienie wasn't authorized to make
contracts. I settled for 50 cents on the dollar
and chalked it up to the fates.
Have you identified errors in the logic offered in many
published pieces on the website and here on the
List that speak to suitability of fuses? If not,
then like the BD-10 episode, it's a matter of preference.
Breakers and their panels are not unsafe. They're
only heavier, more expensive, take up panel space,
require hours of fabrication time, restrict
wire bundle routing options, offer no enhanced level
of safety and MAY be distracting to a pilot who should
be doing more important things.
But if one chooses breakers, they're in good company.
The vast majority of the GA fleet is carrying tons
of them around the sky with a vanishingly small
probability that any single breaker will ever be
called upon to do its job.
Bob . . .
Message 13
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Subject: | Re: Battery Bus Location |
At 10:00 AM 1/6/2010, you wrote:
>
>[/quote]
> The length isn't a REALLY BIG thing, just a
> good practice design rule adopted by the TC
> side of the house many years ago. How long would
> the wire be for both extending the battery
> feeder AND ease of maintenance?
>
> I think i could get by with 18-24" depending on how "easily
> maintainable" it is.
>
>While it's really too cold to heat the shop up for a couple hours, I
>think I'll see if I can find a covered fuse block until I'm back in
>the shop over the weekend
Think about building a cover. The fuse-blocks mount with 4
screws. The "nut" for each of those fasteners could be a
thru-hole, threaded spacer of sufficient height to just clear
the tops of the fuses.
Four thumb-nut screws would be used to mount the cover
down to the tops of the spacers.
A cover might be nothing more than a sheet with four
folded down edges having notches for clearing
wire bundles. I've been thinking about having some ABS
covers made. A friend of mine does deep vacuum forming as
a part of his manufacturing operations. Another option is
to make the cover out of copper clad. See:
http://www.aeroelectric.com/articles/cladboard/cladboard.html
http://aeroelectric.com/Pictures/Data_Acquisition/Weeder_Module_DAS_1.jpg
http://aeroelectric.com/Pictures/Data_Acquisition/Weeder_Module_DAS_2.jpg
I've built robust enclosures out of this stuff. You only need
to cut some accurate rectangular pieces, fixture them
against square corners for soldering, run a bead of solder
down the inside corner for assembly. Single sided clad
gives you a fiberglas/epoxy outside surface that takes paint
very nicely.
Bob . . .
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Subject: | Re: Battery Bus Location |
><snip> I would rather
>have 1 mechanically robust wire than several smaller wires that might be
>subject to chaffing and damage- the fat wire is much easier to protect
>mechanically. Not ideal, but adapted to the situation that I have...
The legacy rationale for incorporating an always hot wire
into an airframe recognizes the limited ability of circuits
protected at 5A or less to start post-crash fires.
Extending the battery bus on a long feeder calls for
protection of that feeder at some current level larger
(and SLOWER) than total draw of accessories fed by the
battery bus. Further, one should consider the dynamics
of interaction between fuses at the bus and protection
at the source end of the feeder. Bus feeders are generally
CURRENT LIMITERS with high tolerance to overload. If a
fast fuse is used upstream of a bus of fast fuses, one
needs to make sure that popping a bus fuse doesn't take
the upstream fuse too. Remember that the upstream fuse
is "pre-heated" by total loads on the battery bus.
Faulting one of the 5A fuses on the bus could trip a
20A feeder protection and take the whole bus down.
When the case is finally adjudicated, I'll be able
to share how a stack-up of "little details" about fault-
trip dynamics brought down a nearly new, very expensive
airplane while getting folks hurt in the process.
If the battery bus is back in the tail, then any
feeders coming forward don't need extra-ordinary
protection. They're lightly fused and risks for
faulting any single feeder are low. Once the bus
feeder turns into a fat wire, the legacy design
philosophy for always hot wires is worthy of
consideration.
Bob . . .
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Subject: | Re: Tachometer problems |
>Could anyone suggest some specific combination of
>capacitor/resistor/diode inline or parallel to the tacho I could try
>to smooth things out? Failed to get any help from VDO so any
>advice would be very much appreciated.
It's a WAG. Without knowing how the input circuits
of the tachometer are crafted, then it's VERY difficult
to figure out what it doesn't like about the signal
provided by your magneto p-leads. The fact that
the reading "drops" suggests a low signal level
. . . hard to imagine on a p-lead!
However, the VDO input signal conditioning may have
over-attenuated the incoming signal as a by-product
of their own design goals for signal conditioning.
In this case, there's not much you can do outside
the tach short of building some sort of signal-
conditioning device to satisfy the tachometer's
demands.
Bob . . .
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Subject: | Re: Question about 16V POLYFUSER Radial Leaded |
Resettable PTC
At 10:23 PM 1/5/2010, you wrote:
>
>I have an EXP bus that I have been considering for my
>project. (That I got for a $40, delivered.) It looks like a slick unit
>
>Sorry, just don't see the design as having much of a downside. If
>you think you may accidentally turn the thing back on, put some red
>tape on the switch or something...pull the wire.
Have you read the discussions on this topic?
Goto http://aeroelectric.com and do a a site
search on . . .
exp bus
Keep in mind that a polyswitch MUST be powered to
STAY tripped. Fault current is reduced to a "safe"
level thus keeping it hot after a trip.
Bob . . .
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Subject: | RE: AeroElectric-List Digest: 16 Msgs - 01/05/10 |
Hi guys=2C (I wish there were some girls here too=2C then I wouldn't have t
o waste time on Facebook)
I've been listening here for a few years while building my Murphy Rebel=2C
and now I think I'm actually ready to start wiring. I'm planning to use Z-1
1 and have an occasional-IFR panel with a Garmin 430 and Dynon EFIS. I'm st
ill at the very basic planning phase. I already have a Plane Power 60amp IR
alternator and a Skytec starter to go on my O-320. That's it=2C the rest i
s a blank sheet of paper. I am starting to visualize wire routing and compo
nent placement. I have a couple of beginner questions at this point to help
with this visualization process:
1)With the P.P. alternator I will obviously not have the seperate voltage r
egulator=2C but do I still need the crowbar over voltage protection?
2)The Skytec starter has it's own contactor to engage the gear=2C and apply
power to the motor. According to Skytec=2C I don't need a seperate contact
or for the starter if I use a 20+amp starter switch=2C which I plan to do (
toggle mag switches and seperate starter switch) Are there any cautions for
not using a seperate starter contactor?
Thanks.
Jesse
_________________________________________________________________
Hotmail: Free=2C trusted and rich email service.
Message 18
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Subject: | RE: [AeroElectric-List] Questions about circuit protection |
Dear Dan
I shouldn't be a pilot (which I am for over 32 years now), I didn't design
or labelled very well my electrical system (which I've done many times),
then, with all the respect, you shouldn't be commenting. sir!
Best regards
Carlos
P.S. You probably didn't read the part of my last comment (the only in which
I didn't panic) when I said I built and fly one airplane with fuses, one
airplane with circuit breakers, and the one I'm currently finishing building
have both. Don't loose your time, just hit the delete button
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-
> server@matronics.com] On Behalf Of Dan Brown
> Sent: quarta-feira, 6 de Janeiro de 2010 16:02
> To: aeroelectric-list@matronics.com
> Subject: RE: AeroElectric-List: RE: [AeroElectric-List] Questions about
circuit
> protection
>
>
> Quoting Carlos Trigo <trigo@mail.telepac.pt>:
>
> > 2) You are flying along in your airplane with Fuses, the radio goes
dead,
> > and nothing else happens. What do you do? Fly the airplane!! not
knowing
> > what happened. Did I loose the alternator? Is there anything that is
going
> > to start a fire? What should I do? Should I land ASAP? Shall I declare
an
> > emergency? Next, anything can happen to the pilot, even panic
>
> Losing the alternator won't take out the radio, unless you don't have
> a battery (in which case it will take out everything electrical).
> Losing the alternator will, however, activate the low-voltage warning
> that you have installed (don't you?), letting you know that you're
> running on battery power. If you're panicking (as most of your
> questions sound like) over losing one radio, you probably shouldn't be
> a pilot.
>
> > When you get on the ground you troubleshoot the problem. If it was a
fuse,
> > it can take some time to find out which.
>
> If it takes you more than 30 seconds to find which fuse goes to that
> radio, you haven't designed or labeled your electrical system very well.
>
> --
> Dan Brown, KE6MKS, dan@familybrown.org
> "Since all the world is but a story, it were well for thee to buy the
> more enduring story rather than the story that is less enduring."
> -- The Judgment of St. Colum Cille
>
>
>
>
>
Message 19
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Subject: | Re: Question about 16V POLYFUSER Radial Leaded |
Resettable PTC
I set the premise poorly - let me try again.
On alert, operating a nuclear delivery system, the goal is to maintain
maximum operational capability and flexibility. To that end, the Technical
Order REQUIRED _one_ attempt to restore a tripped circuit breaker, forbade
more than one attempt, and also forbade holding an offending CB closed. In
this situation, the down side to leaving the switch OFF is some reduction in
either capability or flexibility, depending (of course) on which system is
compromised.
On the other hand, NOTHING electrical (except the spark-maker) on my RV is
so critical to my continued survival that it will require troubleshooting
before I get on the ground comfortably. My panel contains exactly one
breaker - the Crowbar OVM. If it trips, I leave it alone, enable the SD8
and decide whether to land soon or later.
============
Neal...having spent some time in the military myself, I know there is ofter
not much thinking that is to be done, and a procedure for almost
everything...
That being said and that we are no longer held to that kind of procedure,
what's the down side to leaving the switch off?
No one says you have to reset it.
My understanding is that once the electrons are removed from the circuit,
it's dead.
Message 20
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Subject: | Re: RE: [AeroElectric-List] Questions about circuit |
protection
This fuse versus CB discussion raises this questions with me - perhaps
someone can clear it up.
Are any of the current/modern avionic boxes really depending on the CB
or fuse for their internal 'protection' of anything?
I know many units specify a fuse/CB size and sometimes a wire size but I
just size the fuse to protect the wire and try to use a limited number
of adequate wire sizes. My understanding is that various units have
various means of protecting themselves from spikes, etc. And if any kind
of failure starts drawing more amps than the wire/fuse/cb can provide,
pop goes the external protection.
So I'm thinking that if the radio fails, it fails and I use the backup
radio.
If the wire leading to the radio shorts on rough edge or something, the
radio fails and I use the backup radio.
And since fuses are so cheap, I have a separate circuit for practically
every unit on the panel so there is a 1:1 ratio between units and fuses.
If multiple things fail, then it's an electrical system problem -
haven't worked out the details yet but I hope on my Z-14, I just
crossfeed to use the backup Alt/Batt system or otherwise go to the backups.
And if it smokes, open the windows, make sure it stopped smoking or hit
a master until it does. Land ASAP.
What are the holes in this thinking?
Carlos Trigo wrote
> *.Two simple examples:*
> * *
> *1)** **You are flying along in your airplane with **circuit breakers**, the
radio goes dead, and a breaker button pops out. What do you do? **Fly the
airplane**, knowing that something happened in the electric circuit that is protected
by that particular circuit breaker. If the radio (or anything else that
went dead) is not critical to your flight, you complete it with no other worries*
> *2)** **You are flying along in your airplane with **Fuses**, the radio goes
dead, and nothing else happens. **What do you do? **Fly the airplane!!** not
knowing what happened. Did I loose the alternator? Is there anything that
is going to start a fire? What should I do? Should I land ASAP? Shall I declare
an emergency? Next, anything can happen to the pilot, even panic*
> * *
> *When you get on the ground you troubleshoot the problem. **If it was a fuse,
it can take some time to find out which. If it was a circuit breaker, I will
go IMMEDIATELY to the source of the problem*
> * *
> *If the added cost for the row of little buttons to pop out, on the dash, gives
you a sense of security, I say GO FOR IT......** I have 1 airplane with fuses,
1 airplane with cbs, and the one Im finishing building have both. Not biased,
though **J** Only analysing pros and cons*
> * *
> *Carlos*
> * *
> * *
> *
>
>
> *
Message 21
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Subject: | Electrical System Planning |
At 11:45 AM 1/6/2010, you wrote:
I'm planning to use Z-11 and have an occasional-IFR panel with a
Grmin 430 and Dynon EFIS. I'm still at the very basic planning phase.
Do you plan to have vacuum driven instruments?
If not why not Z13/8?
1)With the P.P. alternator I will obviously not have the separate
voltage regulator, but do I still need the crowbar over voltage protection?
Plane Power INCLUDES crowbar OV protection on their OBAM
aircraft alternators.
2)The Skytec starter has it's own contactor to engage the gear, and
apply power to the motor. According to Skytec, I don't need a
separate contactor for the starter if I use a 20+amp starter switch,
which I plan to do (toggle mag switches and separate starter switch)
Are there any cautions for not using a separate starter contactor?
No.
Bob . . .
Message 22
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Subject: | RE: [AeroElectric-List] Questions about circuit protection |
'Lectric Bob
I do agree with you. Fuses have many technical advantages, weight, price,
simplicity of wiring and others.
I also agree with you that it is a matter of choice or preference.
That's why, in my perspective as a pilot, I do prefer circuit breakers.
>From me, end of discussion.
Thanks
Carlos
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: quarta-feira, 6 de Janeiro de 2010 16:55
Subject: Re: AeroElectric-List: RE: [AeroElectric-List] Questions about
circuit protection
At 07:00 PM 1/5/2010, you wrote:
Bob
I really don't want to resuscitate this discussion but, even being aware of
the technical advantages of fuses versus circuit breakers, it is indeed
almost impossible to convince a pilot that a fuse is better than a circuit
breaker.
It has never been offered as 'better' . . . only
adequate to the task of meeting design goals in
a failure tolerant system.
In flight, when a fuse blows, the pilot will hardly notice it, and even if
some device (whose circuit was protected by that fuse) becomes blank, he
will not know if it was the fuse or anything else that caused that device to
die.
Have you read . . .
http://www.aeroelectric.com/articles/fusvbkr2.html
If a circuit breaker pops out, there is a big probability the pilot will
immediately notice it, or at least after seeing any device die, he will
immediately look to the circuit breakers heads to look for the one that
popped out.
Being a pilot trained for so many things, he must also know that he shall
not push that particular breaker in, unless he wants to light up the fire
which will burn his own ass.
It's not clear that you embrace/understand the
rationale presented for unreachable fuse-blocks.
Certainly everyone has a choice to make and
in the final analysis it's personal. I did a
power distribution diagram for the BD-10 jet
about 15 years ago. I bounced the idea of fuse-blocks
off the electrical systems wienie. He agreed that
they were adequate to the task but opined that
anyone building a BD-10 wanted that "busy fighter
cockpit look. The more knobs, buttons and switches
the better." But even after the drawing was completed
using breakers throughout, he about had a cow when
I put about a dozen breakers back in the engine
compartment. The architecture called for protection
in these feeders and the sources for those feeders
were in the tail. Further, there was no failure
mode effects analysis that supported any need for
pilot access to these breakers whatsoever. Nonetheless,
he insisted on having all breakers in the cockpit.
I submitted my bill for work accomplished to date
and bowed out of the project. Got a nastygram from
Mr. Bede hisself honking about the fee and stating
that his electro-wienie wasn't authorized to make
contracts. I settled for 50 cents on the dollar
and chalked it up to the fates.
Have you identified errors in the logic offered in many
published pieces on the website and here on the
List that speak to suitability of fuses? If not,
then like the BD-10 episode, it's a matter of preference.
Breakers and their panels are not unsafe. They're
only heavier, more expensive, take up panel space,
require hours of fabrication time, restrict
wire bundle routing options, offer no enhanced level
of safety and MAY be distracting to a pilot who should
be doing more important things.
But if one chooses breakers, they're in good company.
The vast majority of the GA fleet is carrying tons
of them around the sky with a vanishingly small
probability that any single breaker will ever be
called upon to do its job.
Bob . . .
Message 23
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Subject: | RE: [AeroElectric-List] Questions about circuit |
protection
Dear Dan
I shouldn't be a pilot (which I am for over 32 years now), I didn't
design
or labelled very well my electrical system (which I've done many times),
then, with all the respect, you shouldn't be commenting. sir!
Best regards
Carlos
P.S. You probably didn't read the part of my last comment (the only in
which
I didn't panic) when I said I built and fly one airplane with fuses, one
airplane with circuit breakers, and the one I'm currently finishing
building
have both. Don't loose your time, just hit the delete button
Carlos, my friend,
You have apparently made up your mind that circuit breakers are superior
to
fuses, even though several people on the forum have tried to show you
the
logic and advantages of fuses.
May I suggest that you finish building your aircraft, using resettable
circuit breakers, since this gives you a greater comfort level.
Roger
Message 24
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Subject: | RE: [AeroElectric-List] Questions about circuit |
protection
If multiple things fail, then it's an electrical system problem -
haven't worked out the details yet but I hope on my Z-14, I just
crossfeed to use the backup Alt/Batt system or otherwise go to the
backups.
And if it smokes, open the windows, make sure it stopped smoking or hit
a master until it does. Land ASAP.
Bill,
I think you have it right! However if I had multiple
failures, I believe that I would be heading for "Terra Firma" without
delay.
Roger
Message 25
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Subject: | Re: Question about 16V POLYFUSER Radial Leaded |
Resettable PTC
With regards to the use of Polyfues I believe there was something in
a recent issue of Kit Planes (hunting for it now) that the FAA does
not accept their use in certified aircraft - some thing about if
there is a problem with a circuit they want the circuit protection to
keep the circuit disabled and not to re-energize itself
automatically. You may be able to use them in experimental but if
your building in Sport LSA, that may be an issue. I'm trying to find
the issue and page where I read this.
jerb
At 08:23 PM 1/5/2010, you wrote:
>
>I have an EXP bus that I have been considering for my
>project. (That I got for a $40, delivered.) It looks like a slick unit.
>
>I can understand the concern for a circuit resetting itself after
>the power is restored...but isn't that a reason we put switches on
>things?...Like leave that circuit off if it has a problem...
>
>Sorry, just don't see the design as having much of a downside. If
>you think you may accidentally turn the thing back on, put some red
>tape on the switch or something...pull the wire.
>
>Al
>
>
>Read this topic online here:
>
>http://forums.matronics.com/viewtopic.php?p=280326#280326
>
>
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At 12:55 PM 1/6/2010, you wrote:
>
>P.S. You probably didn't read the part of my last comment (the only
>in which I didn't panic) when I said I built and fly one airplane
>with fuses, one airplane with circuit breakers, and the one I'm
>currently finishing building have both. Don't loose your time, just
>hit the delete button
>
>
>May I suggest that you finish building your aircraft, using
>resettable circuit breakers, since this gives you a greater comfort level.
>
>
>Roger
>
Gentlemen, this isn't about "superiority" of anything over
anything else. It's about meeting design goals for what
we hope will be a failure tolerant system understood by
the pilot and sufficiently fitted to meet the missions
for which the airplane is built.
The pantry of electro-goodies that can be stirred into
a host of recipes for success is huge. Just because any
one of us has a preference over one ingredient vs. another
should not be taken as an invitation to cast disparaging
remarks.
The mission for each of us on the List is to offer/acquire
understanding of how each ingredient functions in
particular situations . . . and not to suggest that anyone
has made a poor choice EXCEPT where we perceive a risk
for not achieving failure tolerance . . . even if the
"preferred" system is heavier, costlier, perhaps more
complex, or uses breakers.
We have a number of folks putting Z-14 into two-place
airplanes with missions that will never tax the system's
ability to mitigate risk. At the same time, for
each individual on the List who has expressed an interest
in exploring the possibilities, there are many, Many,
MANY more who are wiring their airplanes like a 1969
C-172. Are those folks at extra-ordinary risk for a bad
day in the cockpit? No, a modern alternator, active notification
of LV, modern RG battery and a purpose-driven battery
maintenance program makes them 10x better off than we
were in 1950 with generators and lead-acid slop-pots.
The OBAM aviation community, indeed all of light aircraft GA
is under incremental, relentless attack to simply go away.
Our collective future is best served by helping every
OBAM aircraft builder generate and meet design goals consistent
with the best we know how to do . . . while accommodating their
preferences.
Bob . . .
Message 27
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Subject: | Z-14 Switch Combos |
Thanks Bob...
I'll make it a DPDT and use the second pole for a nag-light indicating
the x-feed switch is closed.
Great design. Thanks for saving us a bunch of work.
Phil
-----Original Message-----
From: Robert L. Nuckolls, III [mailto:nuckolls.bob@aeroelectric.com]
Sent: Wednesday, January 06, 2010 10:32 AM
Subject: RE: AeroElectric-List: Z-14 Switch Combos
<nuckolls.bob@aeroelectric.com>
At 10:19 AM 1/6/2010, you wrote:
<Phil.Perry@netapp.com>
>
>Hey Bob,
>
>It looks like the crossfeed switch doubles as a starter switch in your
>diagram, is that correct?
Yes . . . it's spring loaded out of the start position.
It offers automatic closure of the cross-feed contactor
during start.
>I'm planning on going with a push button to start, so I'll probably
>modify the setup slightly. But just want to make sure I'm reading it
>correctly.
Then the cross-feed switch can be SPST.
Bob . . .
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