Today's Message Index:
----------------------
1. 08:18 AM - Re: Fw: Transponder arial location (Robert L. Nuckolls, III)
2. 08:35 AM - Re: Battery dumps (Mike Holland)
3. 09:09 AM - Re: loadmeters (Robert L. Nuckolls, III)
4. 01:52 PM - Dual battery voltage monitoring with alarm (Scott, Ian)
5. 03:29 PM - Dynon Remote Compass mounting? (Kevin Horton)
6. 04:19 PM - Re: Re: Battery dumps (Robert L. Nuckolls, III)
7. 04:21 PM - Re: B-lead to contactor or to battery? (Robert L. Nuckolls, III)
8. 04:50 PM - Re: Re: Battery dumps (Robert L. Nuckolls, III)
9. 04:52 PM - Re: Dynon Remote Compass mounting? (Robert L. Nuckolls, III)
10. 05:02 PM - Re: Dual battery voltage monitoring with (Robert L. Nuckolls, III)
11. 05:09 PM - Re: Help with Diagnosis (Robert L. Nuckolls, III)
12. 05:12 PM - Re: Alternator (Robert L. Nuckolls, III)
13. 05:15 PM - Re: Weird LED fuse behavior (Gilles St-Pierre)
14. 06:14 PM - Re: Re: Battery dumps (Jim Jewell)
15. 07:24 PM - Re: Re: Battery dumps (David Carter)
16. 09:23 PM - Re: Re: Battery dumps (Paul Messinger)
17. 09:50 PM - Re: Re: Battery dumps (Paul Messinger)
Message 1
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| Subject: | Re: Fw: Transponder arial location |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 10:07 PM 2/28/2004 -0700, you wrote:
>--> AeroElectric-List message posted by: "Rick Fogerson" <rickf@cableone.net>
>
>
>----- Original Message -----
>From: Rick Fogerson
>To: aeroelectric-list@matronics.com
>Subject: Transponder arial location
>
>
>Hi Bob,
>I've got a xpdr arial question for you. I have installed that little 3
>inch long arial with a ball (B&C) belly just aft of the firewall between
>the exhaust pipes. The arial would be shielded some in the forward
>direction by the portion of the lower cowl where cooling air exits and the
>exhaust pipes emerge from the engine compartment. That wasn't a problem
>when I was going to install the standard frp cowl but now I thinking of
>trying to build an aluminum cowl. How much of a problem do you think this
>would be?
There's no way to deduced effects of proximity without
going to the antenna range and doing real-time tests
or doing a computerized study with some rather expensive
hardware.
Probability is that complaints from ground controllers
concerning readability of your transponder will be rare
if you position the antenna as you describe.
Bob . . .
Message 2
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| Subject: | Re: Battery dumps |
--> AeroElectric-List message posted by: "Mike Holland" <hollandm@pacbell.net>
Bob, etal. my main concern isn't pilot error but a crowbar induced disconnect
of my Z24 contactor. I understand that this device has proven reliable but it
is a device and together with the contactor and all the necessary wiring, is
a system with multiple failure modes. Estimating the aggregate improbability
of this would be difficult but I'm sure it isn't zero.
I have two main concerns; avoiding dark and stormy night stories and protecting
expensive gadgets. For those (like me) who have rudimentary electrical understanding,
and given the proven issues around disconnecting alternators in-flight,
why do we provide separate control of alternators in airplanes at all?
Why not do what is done is cars and wire b-leads to the battery though fat in-line
fuses? Any smoke would be confined to the engine compartment and my load
meter would instantly tell me I have dropped one or more alternators and to
start looking for a place to land.
And whether the fried regulator is internal/external would seem to be beside the
point since regulator quality and design is the key, and not where it is physically
located.
As someone still building but trying to follow diligently your excellent advise,
I find all this a bit daunting.
In spite of apprehensions they inspire I appreciate the enlightening discussions.
Eventually they will lead to improved designs. It does concern me that focus
of the discussion appears to be taking us in the direction of greater, not
less, complexity. Isn't there a simpler strategy that would potentially sacrifice
a regulator (internal or external) and protect avionics?
Mike Holland
Message 3
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--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 05:52 PM 2/28/2004 -0600, you wrote:
>--> AeroElectric-List message posted by: "Tom Barter"
><kesleyel@IowaTelecom.net>
>
>Bob,
>What is your current recommendation for a loadmeter? Searching the
>archives indicates that the loadmeter kits are no longer available. Is
>there another instrument available that can be modified to indicate system
>load rather than the minus -0 -plus ammeter?
>Thanks,
Sure . . . sorta. The generic loadmeter is an instrument that
reads full scale with 50 millivolts impressed across the
terminals and a scale plate that read either 0-100% or
0 to some value commensurate with the size of the shunt.
Exemplar displays can be seen at:
http://www.aeroelectric.com/Pictures/load-ammeter.jpg
In years gone by, analog instruments like those depicted
above were the norm. Many production aircraft like the
Beechjet still have these exact same instruments in the
cockpit overhead as both voltmeters and loadmeters (NOT
expanded scale voltmeters however). There used to be
many fine houses that produced moving coil, pivot and
jewel instruments in all sizes . . . many of them
small enough and rugged enough to be attractive to
the airplane designer.
Nowadays, and in particular in the OBAM aircraft community,
electrical data readouts are more often being supplied
as part of comprehensive instrumentation packages like
Vision-Microsystems in digital or digital/quasi-analog
displays.
We know that inclusion of voltage and/or loads data
on the panel is most useful for diagnostics. In the
thoughtfully designed and maintained electrical system
there is little value in "knowing the numbers" when
it comes to dealing with electrical system adversity
in flight.
I'd be quite comfortable flying an airplane with
a (1) e-bus, (2) battery selected and maintained
so as to support e-bus loads for duration of fuel
aboard and (3) LV warning light such as I've depicted
at:
http://www.aeroelectric.com/Catalog/AEC/9005/9005-701B.pdf
You may be aware of a product I used to offer that
added some diagnostic instrumentation to a low voltage
warning light shown in
http://www.aeroelectric.com/temp/9021704F.pdf and
http://www.aeroelectric.com/temp/loadvolt.jpg
I discontinued that product due to high rate of return
on the custom instrument made for me by Westach. The
majority of their product plays well but I had about
10-15% return on their instruments for various reasons
and experienced what I felt was poor attitude about
making good on their products.
I am currently considering a new product . . . based
on instruments by a very capable, old-line instrument
manufacturer. They're well built, rugged 1.5" square
meters and easily modified to the specific tasks of
loadmeter and expanded scale voltmeters. You can see
the loadmeter prototype at:
http://www.aeroelectric.com/Pictures/Loadmeter_2.jpg
To successfully bring this product to the marketplace,
I need to invest a pretty big chunk of up-front dollars
to acquire several years worth of "stock" instruments
for production and spares.
Given the shift to digital instrumentation -AND-
the reality that putting these instruments on the
panel is a help only to the mechanic and not the
pilot . . . I'm wrestling with the decision to
stock up on raw-material instruments.
I approached Mitchell a few months ago about doing
these instruments but they declined. They may have
the same foreboding about the future of steam gages
on panels and/or it may be that they don't appreciate
the potential for servicing the OBAM aircraft community.
At the moment, it appears that if a reasonably
priced, quality set of instruments are going to
come to the market as either loadmeters, voltmeters
or any other task, I'm going to have to do it.
I expect to make up my mind in the next 30 days
or so.
Irrespective of how all the decisions shake out,
I cannot get excited about putting a -0+ reading
battery-ammeter in an airplane.
Bob . . .
Message 4
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| Subject: | Dual battery voltage monitoring with alarm |
--> AeroElectric-List message posted by: "Scott, Ian" <ian_scott@commander.com>
this is a marine instrument designed for 3 battery banks, however would seem to
work fine for dual battery installs.
http://www.cruzpro.com/v30.html
Ian
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Message 5
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aeroelectric-list@matronics.com
| Subject: | Dynon Remote Compass mounting? |
--> AeroElectric-List message posted by: Kevin Horton <khorton01@rogers.com>
I'm pondering the details of how to mount the remote compass sensor
for my Dynon EFIS. I'm leaning towards hanging it from the top of
the F-809 bulkhead on my RV-8, somewhat similar to:
http://home.comcast.net/~jwdanie/Compass/compass.html
But, I'm worried about potential interference from the high voltage
strobe light line that goes from the power supply back to the tail
strobe. I could reroute that guy lower, but it will be a real PITA.
So, I'm wondering how close anyone has run a strobe light cable (the
big grey one that goes from the power supply to the light) to the
EDC-10 remote compass mount. If you've got such a strobe line in the
area of your remote compass sensor, tell me how far away it is, and
whether you can see any effect on heading from it.
My strobe cable would probably be about 8 inches from the compass
sensor if I don't move it. I don't want to move it if I can get away
with it.
Thanks,
--
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/
Message 6
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| Subject: | Re: Battery dumps |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 08:34 AM 2/29/2004 -0800, you wrote:
>--> AeroElectric-List message posted by: "Mike Holland" <hollandm@pacbell.net>
>
>Bob, etal. my main concern isn't pilot error but a crowbar induced
>disconnect of my Z24 contactor. I understand that this device has proven
>reliable but it is a device and together with the contactor and all the
>necessary wiring, is a system with multiple failure modes. Estimating the
>aggregate improbability of this would be difficult but I'm sure it isn't zero.
>
>I have two main concerns; avoiding dark and stormy night stories and
>protecting expensive gadgets. For those (like me) who have rudimentary
>electrical understanding, and given the proven issues around disconnecting
>alternators in-flight, why do we provide separate control of alternators
>in airplanes at all?
IF you're wired to include an e-bus and you have ov protection
for the alternator and you plan to maintain a battery such that
it keeps the e-bus alive for duration of fuel aboard, then you
have a failure tolerant system that will deprive you of the
experience of writing a dark-n-stormy night story . . .
Further, unless you're in the habit of flipping the right
switches at the wrong times, you're not at much risk for
an event that causes damage.
>Why not do what is done is cars and wire b-leads to the battery though fat
>in-line fuses? Any smoke would be confined to the engine compartment and
>my load meter would instantly tell me I have dropped one or more
>alternators and to start looking for a place to land.
But when the smoke is coming from some place other than alternator wiring,
how do you make the system totally cold? Looking for a place to land in
response to smoke is to capitulate in the face of and electrical
EMERGENCY . . .
something I try to avoid by thoughtful design and maintenance.
>And whether the fried regulator is internal/external would seem to be
>beside the point since regulator quality and design is the key, and not
>where it is physically located.
>
>As someone still building but trying to follow diligently your excellent
>advise, I find all this a bit daunting.
>
>In spite of apprehensions they inspire I appreciate the enlightening
>discussions. Eventually they will lead to improved designs. It does
>concern me that focus of the discussion appears to be taking us in the
>direction of greater, not less, complexity. Isn't there a simpler
>strategy that would potentially sacrifice a regulator (internal or
>external) and protect avionics?
That's essentially what Z-24 does right now. It unhooks
the runaway alternator to save the system. It seems that
some folks have experienced damage to what WAS a working
alternator by turning the alternator off while it was
loaded.
If you have an externally regulated alternator, 99.99% of this
discussion doesn't apply. The 0.01% that does apply concerns the
loss of battery connection on a system with EITHER internally
OR externally regulated alternators while the alternator is
heavily loaded by battery-recharge current. This is so rare
an event that the A36 P.O.H. (this airplane has totally
independent battery and alternator switches) makes no special
note of sequence of switch operation. In fact, it says
"BATTERY and ALTERNATOR switches - OFF". I suppose if I turn
the battery off first, I have exposed the airplane to a
potential battery-dump event. It wouldn't be difficult
to deliberately generate such an event in the A-36. However,
I have to go out of my way to make it happen and
it doesn't happen in the normal course of operating the
airplane PER the P.O.H.
Don't worry about any of the drum-beating and swinging
of swords for the moment. It's a certainty that when
the investigation is complete and the numbers are known,
there WILL be a simple and effective lotion for
soothing all concerns . . . while making sure that you
never experience an electrical emergency.
Bob . . .
Message 7
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| Subject: | Re: B-lead to contactor or to battery? |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 01:12 AM 2/29/2004 -0600, you wrote:
>--> AeroElectric-List message posted by: "Troy Scott"
><tscott1217@bellsouth.net>
>
>Gentlemen,
>
>I note that all the Z drawings show the alternator B lead connected to a
>contactor rather than directly to a battery or hot bus. Is this necessarily
>always the case? Is this done to facilitate OV protection? Is this more
>appropriate to internally regulated alternators that to externally regulated
>alternators?
Has nothing to do with style of alternator. The goal is to tie
the b-lead of an alternator to the (+) post of the battery
through the shortest practical lengths of FAT wire. Depending
on how things are situated in your airplane, it may make more
sense to locate your b-lead fuse at the battery contactor instead
of the starter contactor. This is a noise and radiated magnetics
issue and applies to all alternators, internally or externally
regulated.
Bob . . .
Message 8
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| Subject: | Re: Battery dumps |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
>
> > Many more radios have been smoked
> > for lack of ov protection than for any other reason. Experience
> > indicates (and DO-160 infers) that once this dragon is adequately
> > chained down, probability of letting lots of smoke out of your
> > radios is very low.
>
>I agree but many of us have older equipment that may not have the type of OV
>protection (per DO -160) to withstand a large "dump" where the voltage
>'seems' to get well over 40 V with a simple 5kw 18v device and a 40 amp
>dump. I have not fully instrumented it as yet.
More that 20 years old? The DO-160 recommendations for robust
accessory design have been around for over 30 years.
>Limiting the selection of equipment to certified to DO-160 is not affordable
>in many cases.
>
>I only have the materials and time to test my own alternator etc and do not
>have a ND internal W/WO external alternator. Thus you may get very
>different results. Sorry but every alternator is likely to be somewhat
>different.
>
>However, if you have a load bank that can handle 14V at 40 amps and use a
>contactor to drop the load you can see what the "dump" is.
I plan to to do that. Do you have numbers to share with us from
tests you've done?
>I have had no damage with the 5kw 18v device I am using in my setup but
>another poster has had failures perhaps only due to the test setup. I am not
>placing the TVS at the alternator but several feet away on the power bus
>distribution and as such have some series resistance external to the
>alternator.
Any resistance will be measured in milliohms . . . given the
self limiting magnitude of current source at or below the
limits of the alternator, I doubt that any series resistance
on this order of magnitude is significant. I suspect that
George exceeded the total energy limits for the device which
is going to be more a function of duration of the dump event
as opposed to large currents.
>Nor do I have the time (or interest) to try to see if all my equipment will
>withstand the resulting OV on the bus. My intent is to clamp the OV at its
>source and or prevent the dump from happening in the first place.
>
>I think we agree that if the battery is never taken off line while being
>charged, there will be no dump. Other than contactor failure your designs
>prevent that IF fully followed. The problem is where a builder fails to see
>the reason for your design detail and changes it.
Kind of, but the A-36 Bonanza has completely separate
alternator and battery switches and the P.O.H. makes no
mention of a need to "properly" sequence switches. If
you operate them like the P.O.H. says, there's no
battery-dump event even when the battery switch is
turned off first.
> >
> > Even then the alternator always goes off first and does NOT have
> > an internal regulator. You can take ANY certified single with
> > the infamous split rocker master switch and punch the alternator
> > and battery off simultaneously by hitting both sides of the
> > switch. This simultaneously disconnects the battery AND the
> > alternator field . . . the mechanically linked nature
> > of the split-rocker COMBINED with the fact that all spam-cans
> > have externally regulated alternators makes this action a non-
> > event with respect to battery dump.
>
>Again disagree with ALL. I fly a friends spam can and he lost the external
>regulator when electrical smoke appeared in the cockpit and he hit the dual
>off rocker. True no avionics were damaged but the alternator regulator was
>fried and this was a factory supplied regulator.
>
>In the above case I believe the battery contactor slow opening time of
>several MS allowed the alternator to shut\down with no "dump".
What's the foundation for that supposition? Where did the smoke
come from? What was the magnitude of current flow into the
battery at the time? How do you know that the right conditions
existed at the time to precipitate a battery-dump event that was
held a bay only because of some contactor drop-out delay?
It's a hypothesis I have difficulty supporting. If the smoke
came from the regulator, this may well have been a simple case
of gross failure within the regulator that prompted the pilot
to take the action he did. If accompanied by an OV event, his
swift action may have been hundreds of milliseconds late . . .
the OV protection system may have already shut down the
alternator.
Like the "Sparks in the Dark" story in chapter 17, there
is a LOT of data missing for understanding root cause
and magnitude/sequence of events.
> > >I am addressing a different case. First, not everyone has your
>progressive
> > >switches;
>
>All of us do not like toggle switches etc and while its fine to suggest you
>use what you have designed in its also worth considering others need to be
>able to provide the same safety with "normal" rockers or other styles that
>are simple not available in sequential design.
Progressives are available in rockers too and certainly two-pole
switches are available. Figure Z-12 shows both poles of the
non-progressive DC MASTER switch used to shut down battery and
alternator simultaneously.
> > Can't help it if the reasoning behind the use of
> > progressive master switches is misunderstood or ignored.
>
>I suspect there are many who do not fully understand. Perhaps I missed it
>but I see no note in appendix Z (just downloaded) describing the requirement
>for the sequential switch.
The 'Connection in not intended to levy REQUIREMENTS upon anyone.
I have added an opening paragraph to Revision 11 Z-drawings
to caution folks that the drawings have features which may
not be readily apparent to the builder but important
to achieve a failure tolerant, trouble free design. Before ANY changes
are implemented, they should get on the AeroElectric-List and
tell us how the as-published drawings fall short of some
perceived goal. There will also be a new note specific to the
DC power master switch that addresses the value in NOT allowing
the alternator to remain on line after the battery is shut
off.
<snip>
>I think we have such a part today. There is a 500 amp TVS designed
>specifically for this subject load dump (mentioned much earlier in ths
>thread as I recall). Not stocked, so I went to the 160 amp 5kw part that was
>in stock. It seems to work for me and should keep the dump event under
>DO-160 testing. However I do have some equipment that appears to be unable
>to pass DO-160 and so I am continuing to investigate.
Can you share a part number with us?
>Perhaps my background in space craft is biasing my thinking. There we did
>what ever was possible to prevent single point failures regardless of
>probability based on real experience that even a 0.0001% probable event can
>and did happen.
>
>Perhaps you would like to know that I recommend your "book" etc to other
>builders and admonish them to follow the the info 100%. Or ask specific
>questions about any deviations (including the use of progressive switches
>:-)
I do appreciate your vote of confidence my friend. I will
do my best to be worthy of it.
Bob . . .
Message 9
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| Subject: | Re: Dynon Remote Compass mounting? |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 06:27 PM 2/29/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: Kevin Horton <khorton01@rogers.com>
>
>I'm pondering the details of how to mount the remote compass sensor
>for my Dynon EFIS. I'm leaning towards hanging it from the top of
>the F-809 bulkhead on my RV-8, somewhat similar to:
>
>http://home.comcast.net/~jwdanie/Compass/compass.html
>
>But, I'm worried about potential interference from the high voltage
>strobe light line that goes from the power supply back to the tail
>strobe. I could reroute that guy lower, but it will be a real PITA.
>So, I'm wondering how close anyone has run a strobe light cable (the
>big grey one that goes from the power supply to the light) to the
>EDC-10 remote compass mount. If you've got such a strobe line in the
>area of your remote compass sensor, tell me how far away it is, and
>whether you can see any effect on heading from it.
>
>My strobe cable would probably be about 8 inches from the compass
>sensor if I don't move it. I don't want to move it if I can get away
>with it.
There should be NO magnetic field radiated from your
strobe lines. Don't worry about them affecting your
compass sensor.
Bob . . .
Message 10
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| Subject: | Re: Dual battery voltage monitoring with |
alarm
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
alarm
At 08:51 AM 3/1/2004 +1100, you wrote:
>--> AeroElectric-List message posted by: "Scott, Ian"
><ian_scott@commander.com>
>
>
>this is a marine instrument designed for 3 battery banks, however would
>seem to work fine for dual battery installs.
>
>http://www.cruzpro.com/v30.html
>
>Ian
Cute. I'm mystified as to why it's so BIG . . . 4" deep
over all. Found them offered for sale at this
site:
http://www.emarineinc.com/products/monitors/v30.html
for $129. Seems a reasonable price for the
capability. One could monitor the main bus
and two batteries with this critter. You might
want to power it trough a panel mounted switch.
The published 0.017A draw would run your battery
down in about 6 weeks.
Bob . . .
Message 11
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| Subject: | Re: Help with Diagnosis |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 09:50 PM 2/28/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: Matt Jurotich
><mjurotich@hst.nasa.gov>
>
>My already flying when I bought it RV 6 A has a B&C alternator and a
>LR3C-14 voltage regulator. The builder used a 10 amp fuse in the Field
>line.
This is contrary to recommended installation. Suggest you consider
rewiring to include the suggested 5A breaker per installation
instructions.
> Some months ago when I had a low battery, an attempt to jump the
>battery got a lot of sparks in the vicinity of the LR3C-14.
I am always concerned about reports of "sparks" wherein their
source is not researched and identified. See chapter 17 of
the 'Connection for another sparks-outta-nowhere story.
> About 3 flying
>hours later the fuse blew and we got home on the battery. Today the fuse
>blew again. We landed and replaced the fuse. Everything seemed OK during
>taxi and run-up, but the fuse blew again shortly after take-off. Got home
>on battery again. Since my home airport is in the DC ADIZ this needs to be
>fixed properly. Where do I start to look? A short in the field wire is
>the first place, what next? Thanks in advance for the help.
Do you have any idea where the sparks came from? How
did you observe them? You either have a wiring problem
or the crowbar ov system in the LR3 is being tripped.
How old is the LR-3? There was a mod to the design to
fix an nuisance tripping problem with the OV system but
since your problems seem to post-date another issue
(sparks) with un-explained origin, the LR-3 may be fine
and only the wiring needs investigation. If it were my
airplane, I'd install the recommended 5A breaker, install
ALL new wiring in the field supply circuit and see if
the problem goes away.
If it's still tripping the breaker, we'll need to dig
further.
Bob . . .
Message 12
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--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 09:54 PM 2/27/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: Benford2@aol.com
>
>In a message dated 2/27/2004 7:26:51 PM Mountain Standard Time,
>Bobdeva@aol.com writes:
>
> >
> > Anyone have a source for a good alternator? (Other than B&C.) I want a
> good
> > alternator that is NOT internally regulated. Price is not important, you
> > usually
> > get what you pay for. 40 or 60 amp. for Lyc. O320.
> > Thank you,
> > Bob Devaney
Bob, virtually ALL modern alternators are supplied
from the factory with built in regulators. Your
best bet is to get a junk-yard Nipon-Denso and modify
it yourself or have it modified. Is there a local
alternator shop that could help you?
Bob . . .
Message 13
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| Subject: | Weird LED fuse behavior |
--> AeroElectric-List message posted by: "Gilles St-Pierre" <ranchlaseigneurie@hotmail.com>
most of the time this has something to do with a bad ground .or a loose
connection
bsl aviation
gilles
elite 717
>From: "John Slade" <sladerj@bellsouth.net>
>Reply-To: aeroelectric-list@matronics.com
>To: <aeroelectric-list@matronics.com>
>Subject: AeroElectric-List: Weird LED fuse behavior
>Date: Sat, 28 Feb 2004 22:12:12 -0500
>
>--> AeroElectric-List message posted by: "John Slade"
><sladerj@bellsouth.net>
>
>Here's a strange one for someone....
>
>I have those fuses with an LED that lights up when they blow.
>
>When running my engine for the first time I notice that the LED for the
>fuel
>injection computer (on the essential buss) is glowing, and that the glow
>changes in intensity with rpm - i.e. I can light it up more by pushing the
>throttle. On shut down I find that the fuse is not blown. I'm not seeing
>any
>charge on the buss from the alternator, and I'm wondering if this may have
>something to do with it. Perhaps the alternator solenoid is open, but I
>can't see how that would affect voltage or cause some sort of reverse flow
>effect.
>
>Any ideas anyone?
>John Slade
>Cozy IV turbo rotary - making noise
>
>
Message 14
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| Subject: | Re: Battery dumps |
--> AeroElectric-List message posted by: "Jim Jewell" <jjewell@telus.net>
----- Original Message -----
From: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Subject: Re: AeroElectric-List: Re: Battery dumps
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<bob.nuckolls@cox.net>
>
> At 08:34 AM 2/29/2004 -0800, you wrote:
> >--> AeroElectric-List message posted by: "Mike Holland"
<hollandm@pacbell.net>
> >
> >Bob, etal. my main concern isn't pilot error but a crowbar induced
> >disconnect of my Z24 contactor. I understand that this device has proven
> >reliable but it is a device and together with the contactor and all the
> >necessary wiring, is a system with multiple failure modes. Estimating
the
> >aggregate improbability of this would be difficult but I'm sure it isn't
zero.
> >
> >I have two main concerns; avoiding dark and stormy night stories and
> >protecting expensive gadgets. For those (like me) who have rudimentary
> >electrical understanding, and given the proven issues around
disconnecting
> >alternators in-flight, why do we provide separate control of alternators
> >in airplanes at all?
>
> IF you're wired to include an e-bus and you have ov protection
> for the alternator and you plan to maintain a battery such that
> it keeps the e-bus alive for duration of fuel aboard, then you
> have a failure tolerant system that will deprive you of the
> experience of writing a dark-n-stormy night story . . .
>
> Further, unless you're in the habit of flipping the right
> switches at the wrong times, you're not at much risk for
> an event that causes damage.
>
>
> >Why not do what is done is cars and wire b-leads to the battery though
fat
> >in-line fuses? Any smoke would be confined to the engine compartment and
> >my load meter would instantly tell me I have dropped one or more
> >alternators and to start looking for a place to land.
>
> But when the smoke is coming from some place other than alternator
wiring,
> how do you make the system totally cold? Looking for a place to land
in
> response to smoke is to capitulate in the face of and electrical
> EMERGENCY . . .
> something I try to avoid by thoughtful design and maintenance.
>
>
> >And whether the fried regulator is internal/external would seem to be
> >beside the point since regulator quality and design is the key, and not
> >where it is physically located.
> >
> >As someone still building but trying to follow diligently your excellent
> >advise, I find all this a bit daunting.
> >
> >In spite of apprehensions they inspire I appreciate the enlightening
> >discussions. Eventually they will lead to improved designs. It does
> >concern me that focus of the discussion appears to be taking us in the
> >direction of greater, not less, complexity. Isn't there a simpler
> >strategy that would potentially sacrifice a regulator (internal or
> >external) and protect avionics?
>
> That's essentially what Z-24 does right now. It unhooks
> the runaway alternator to save the system. It seems that
> some folks have experienced damage to what WAS a working
> alternator by turning the alternator off while it was
> loaded.
>
> If you have an externally regulated alternator, 99.99% of this
> discussion doesn't apply. The 0.01% that does apply concerns the
> loss of battery connection on a system with EITHER internally
> OR externally regulated alternators while the alternator is
> heavily loaded by battery-recharge current. This is so rare
> an event that the A36 P.O.H. (this airplane has totally
> independent battery and alternator switches) makes no special
> note of sequence of switch operation. In fact, it says
> "BATTERY and ALTERNATOR switches - OFF". I suppose if I turn
> the battery off first, I have exposed the airplane to a
> potential battery-dump event. It wouldn't be difficult
> to deliberately generate such an event in the A-36. However,
> I have to go out of my way to make it happen and
> it doesn't happen in the normal course of operating the
> airplane PER the P.O.H.
>
> Don't worry about any of the drum-beating and swinging
> of swords for the moment. It's a certainty that when
> the investigation is complete and the numbers are known,
> there WILL be a simple and effective lotion for
> soothing all concerns . . . while making sure that you
> never experience an electrical emergency.
>
> Bob . . .
>
>
Message 15
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| Subject: | Re: Battery dumps |
--> AeroElectric-List message posted by: "David Carter" <dcarter@datarecall.net>
For Bob N. & Paul Messinger, especially, and Eric Jones: I've studied the
sharing of ideas and views on this Battery Dump thing. I believe Mike
Holland's e-mail below (part), which mentions "big in-line fuse" type
device. Fuses & CB all have a "time rating". I believe a big B-Lead fuse
or limiter would be a "slow blow" item.
- I think the discussion should be momentarily limited so we (you!)
focus on the 1 thing that I believe has not, so far, been isolated out and
clearly addressed/responded to: "Time or Duration of the Event before it is
'killed'. "
- Seems to me, if we set aside the reasonable assessment of risk that Bob
has given, and we do that so we can address the "root technical issue", I
believe that issue to be this one of "time".
-- Can the OverVoltageProtection module & associated contactor (OVP
system) open fast enough to prevent the Dump's hi-voltage from getting onto
"main bus" for a long enough time to damage non-DO-160 gadgets?
-- To repeat & expand: If ANYTHING or WHATEVER causes a
"significant" Battery Dump event (i.e., a non-PM alternator producing high
enough volts and current to damage non-DO-160 gadgets if left unmitigated),
then will the OVP system (contactor) open fast enough to limit the time to
____ ms? __ ms being short enough so that there will be no damage caused
by the HI VOLTAGE that WILL go downstream, past the OVP contactor, and into
the "electrical distribution bus" and (potentially finicky) equipment
connected thereto?
David
----- Original Message -----
From: "Mike Holland" <hollandm@pacbell.net>
Subject: AeroElectric-List: Re: Battery dumps
> --> AeroElectric-List message posted by: "Mike Holland"
<hollandm@pacbell.net>
>
> Bob, etal. my main concern isn't pilot error but a crowbar induced
disconnect of my Z24 contactor. I understand that this device has proven
reliable but it is a device and together with the contactor and all the nece
ssary wiring, is a system with multiple failure modes. Estimating the
aggregate improbability of this would be difficult but I'm sure it isn't
zero.
>
> I have two main concerns; avoiding dark and stormy night stories and
protecting expensive gadgets. For those (like me) who have rudimentary
electrical understanding, and given the proven issues around disconnecting
alternators in-flight, why do we provide separate control of alternators in
airplanes at all?
>
> Why not do what is done is cars and wire b-leads to the battery though fat
in-line fuses? Any smoke would be confined to the engine compartment and my
load meter would instantly tell me I have dropped one or more alternators
and to start looking for a place to land.
>
> And whether the fried regulator is internal/external would seem to be
beside the point since regulator quality and design is the key, and not
where it is physically located.
>
> As someone still building but trying to follow diligently your excellent
advise, I find all this a bit daunting.
>
> In spite of apprehensions they inspire I appreciate the enlightening
discussions. Eventually they will lead to improved designs. It does
concern me that focus of the discussion appears to be taking us in the
direction of greater, not less, complexity. Isn't there a simpler strategy
that would potentially sacrifice a regulator (internal or external) and
protect avionics?
>
>
> Mike Holland
>
>
Message 16
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| Subject: | Re: Battery dumps |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<bob.nuckolls@cox.net>
>
>
> More that 20 years old? The DO-160 recommendations for robust
> accessory design have been around for over 30 years.
Recomendations are not requirements and even today, stuff is designed and
sold with no specific verified compliance with DO-160.
> >However, if you have a load bank that can handle 14V at 40 amps and use a
> >contactor to drop the load you can see what the "dump" is.
>
> I plan to to do that. Do you have numbers to share with us from
> tests you've done?
Eventually but what I have so far is not properly instrumented and based on
your past comments about specifics its too soon to provide exact data.
I will post when I have exact data but its will require a better setup for a
chance of repeatable duplication by others.
> >I have had no damage with the 5kw 18v device I am using in my setup but
> >another poster has had failures perhaps only due to the test setup. I am
not
> >placing the TVS at the alternator but several feet away on the power bus
> >distribution and as such have some series resistance external to the
> >alternator.
>
> Any resistance will be measured in milliohms . . . given the
> self limiting magnitude of current source at or below the
> limits of the alternator, I doubt that any series resistance
> on this order of magnitude is significant. I suspect that
> George exceeded the total energy limits for the device which
> is going to be more a function of duration of the dump event
> as opposed to large currents.
Even a small resistance in series with the TVS reduces the peak voltage as
the TVS has a vary low resistance also. I agree that the peak current is
limited to perhaps 150% of the alternator rated output or lower and not the
huge currents seen in some ref material. Also we are not discussing a
shorted output but a alternative path for the excess current for say 40 amps
and the TVS supplies that path at a starting V of around 21V based on the
18V rated unit. The peak voltage then increases from 21V based on the
internal resistance of the TVS. BTW I tested over 100 18V TVS units in both
1.5KW and 5KW ratings and the 21V point was in the range of 20.5V - 21.3V.
Perhaps a 16V TVS would be better but 5KW @16V was not easily available.
> Kind of, but the A-36 Bonanza has completely separate
> alternator and battery switches and the P.O.H. makes no
> mention of a need to "properly" sequence switches. If
> you operate them like the P.O.H. says, there's no
> battery-dump event even when the battery switch is
> turned off first.
Well the S35 I had specifically said the excess fuel was routed to the
selected tank both in writing and on the diagram. NOT so its always routed
to the left tank. Thus with full tanks there was a unmentioned REQUIREMENT
to use the left tank first.
As for no dump how do you know for sure?? with the battery being charged at
a hi rate I would expect some spike with a minimal electrical system load.
After all, load dump is known characteristic of alternators that are
suddenly unloaded regardless of how fast the regulator is. Fast regulators
simply reduce the duration of the event not prevent it.
> >Again disagree with ALL. I fly a friends spam can and he lost the
external
> >regulator when electrical smoke appeared in the cockpit and he hit the
dual
> >off rocker. True no avionics were damaged but the alternator regulator
was
> >fried and this was a factory supplied regulator.
> >
> >In the above case I believe the battery contactor slow opening time of
> >several MS allowed the alternator to shut/down with no "dump".
>
> What's the foundation for that supposition? Where did the smoke
> come from? What was the magnitude of current flow into the
> battery at the time? How do you know that the right conditions
> existed at the time to precipitate a battery-dump event that was
> held a bay only because of some contactor drop-out delay?
I know the pilot and I know the results of the failure investigation and
sorry but the regulator failed as the direct result of opening the
battery/bus loads. The smoke was from a radio.
I suppose its possible the regulator decided to fail at that precise time
but that is unlikely and as there was a sudden complete load load loss there
was a load dump and the only question was did the reg fail from "tired" or
from the load dump.
> Like the "Sparks in the Dark" story in chapter 17, there
> is a LOT of data missing for understanding root cause
> and magnitude/sequence of events.
Frankly I see no reason to spend lots of time trying to supply details as
you seem to have already made up your mind. The events that need to take
place for a load dump are well understood. He had such a case, end of
discussion.
> >I think we have such a part today. There is a 500 amp TVS designed
> >specifically for this subject load dump (mentioned much earlier in ths
> >thread as I recall). Not stocked, so I went to the 160 amp 5kw part that
was
> >in stock. It seems to work for me and should keep the dump event under
> >DO-160 testing. However I do have some equipment that appears to be
unable
> >to pass DO-160 and so I am continuing to investigate.
>
> Can you share a part number with us?
I will look up both part numbers.
Can you tell me the specific details of the OV transient test specified in
DO -160 like rise time, peak V and fall time as well as duration. I have no
free access to the subject document and knowing thst info it would help in
determining if the TVS fix was adequate.
I also am replying to another post on this subject that is of interest to
all of us.
Paul
Message 17
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| Subject: | Re: Battery dumps |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
Excellent point. Perhaps 99.99% of those on the list feel like your comments
and could care less about the finer points etc.
more embedded comments
> --> AeroElectric-List message posted by: "David Carter"
<dcarter@datarecall.net>
>
> For Bob N. & Paul Messinger, especially, and Eric Jones:
> -- Can the OverVoltageProtection module & associated contactor
(OVP
> system) open fast enough to prevent the Dump's hi-voltage from getting
onto
> "main bus" for a long enough time to damage non-DO-160 gadgets?
ANY voltage over 20V for a TBD time can be a potential problem (at least
with some gadgets) and the issue is what is TBD. A power contactor can take
several MS to open and that time is increased a little by the diode we
install across the contacts. Further the OVP module has a built in time
delay to trip as its intended to detect failure to regulate, not spikes.
As you point out one key is the time to open. It would appear (to me) that
time could be as long as 5 ms. Some contactors are faster to open than
others and we have another variable to consider. Another question is what is
the V spike during this time and will this damage equipment.
I have asked Bob for the details of the "test" spike that DO-160 requires
equipment to pass. We must first be sure that any load dump solution is
inside that test spike. The final question is what about the other non
complying "gadgets" and that is an individual question as there are so many
variables.
I have what seems to work for me nut as you have read its not fully tested
as a proper test requires (lots of setup here) and that is not simple for me
as its dealing with huge (to me) currents. I do have the equipment to
properly monitor and record the event. What is a quick and dirty test that
convinces me is no where enough for the rest of the world including Bob. ;-)
In any event I am working on getting info that can be repeated and should
solve the problem with a simple fix.
The 500Amp TVS I have mentioned is specifically designed for load dump
protection and is designed to fail short if overloaded. This is not
necessarly a solution for us as the clamp voltage may be too high for us as
its inteneded for auto use.
I have started on getting samples but this can take a lot of time based on
past experience with that mfgr.
Paul
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