Today's Message Index:
----------------------
1. 12:59 AM - Re: Co-ax splice method (Ron Koyich)
2. 05:20 AM - Re: Co-ax splice method (Ron Koyich)
3. 06:02 AM - Re: Re: What's all this load dump stuff anyway? (Paul Messinger)
4. 07:16 AM - DO-160 (Paul Messinger)
5. 07:16 AM - LOAD DUMP TEST START (Paul Messinger)
6. 08:01 AM - Re: Co-ax splice method (Robert L. Nuckolls, III)
7. 08:02 AM - Re: For Bob Nuckolls: Roll your own (Robert L. Nuckolls, III)
8. 08:04 AM - Re: DO-160 (Robert L. Nuckolls, III)
9. 08:51 AM - Re: DO-160 (Paul Messinger)
10. 09:13 AM - Re: LOAD DUMP TEST START (Robert L. Nuckolls, III)
11. 10:20 AM - FS - EGT/CHT probes (richard@riley.net)
12. 10:28 AM - Re: Re: LOAD DUMP TEST START (Paul Messinger)
13. 12:19 PM - Re: Antenna Placement (Ross Mickey)
Message 1
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| Subject: | Co-ax splice method |
--> AeroElectric-List message posted by: "Ron Koyich" <Ron@Koyich.com>
>>I could just install a male connector on one and a female connector on
the other, then mate them and cover with some heatshrink. Is this the
best approach to this situation? Thanks for your advice!<<
That would be good practice, Keith.
Using crimp-on connectors and making sure the connectors were installed
correctly with low resistance before covered them.
Another option, rather than heatshrink, would be the NITO type self
vulcanizing tape (rubber with no sticky side - pulling the tape tight
over the previous wrap seals the connection). It's good in any harsh
environment - keeps moisture out of the connection. If your plane will
be kept in a high humidity environment you might consider it.
Ron
Message 2
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| Subject: | Co-ax splice method |
--> AeroElectric-List message posted by: "Ron Koyich" <Ron@Koyich.com>
>>before covered them<<
Edit - Edit
...before you covered them.
Of course....
Message 3
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| Subject: | Re: What's all this load dump stuff anyway? |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
I know but picking that part is premature as to date. ALL the discussion is
based on NO real data just what mfgrs have used for their own purposes.
There are much sturdier parts available at much lower cost not that cost is
a driver here.
Paul
----- Original Message -----
From: <jmfpublic@comcast.net>
<Aeroelectric-List@matronics.com>
Subject: AeroElectric-List: Re: What's all this load dump stuff anyway?
> --> AeroElectric-List message posted by: jmfpublic@comcast.net
>
> Paul and Bob,
>
> The MR2535 is $1.45, minimum order 10 units from Digikey. Using 5 of them
should not be a problem.
>
> Jim Foerster
>
Message 4
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--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
Bob,
I would like to know the DO-160 requirements associated with transients
above say 24V including pulse duration, shape and peak V where the duration
is under one second.
For example I recall there is a 40V pulse but I do not know its duration or
shape. I seem to recall there is a longer pulse at a lower voltage also.
Then there is the maximum Voltage steady state level. And perhaps others
addressing above normal bus voltage ranges.
This info will help me with the load dump testing. Specifically IF I find
what appears to be a condition that exceeds DO-160 requirements. In that
case I want to further analize the test results and it would also be a
factor in any proposed solution which would be a final part of the load dump
tests.
Paul
Message 5
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| Subject: | LOAD DUMP TEST START |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
The long waited REAL testing started on 5-13-04.
This will take as long as it takes :-) at a rate of a couple of hours per
day, but likely completed this month. (Could also be less than a week to
preliminary final results, full writeup/documentation may take months.)
Its not simple to design a test of this complexity when the results will
subject to the likes of Bob :-). I have some preconsived ideas of the
results (as do many of us, including Bob, but have set that aside and will
let the results stand for themselves. The test conditions are designed to
allow others to duplicate with reasonable accuract what I am doing so any or
all parts can be setuip in a different lab and the results should be
comparable considering the component and test equipment variations.
System level Load Dump is not a simple issue as some have tried to make it.
That is IF the objective is to detail what happens and how it can effect the
other parts of the system. Even the OVP module is part of the system during
the time it takes to open the associated 5 amp CB.
Only protection of the alternator internal diodes and regulator is one
solution and that only takes clamping the voltage to 35-40 volts and that
voltage is way too high for some equipment including some of mine.
Others will accept the above as enough and TRUST the rest of their system
meets DO-160 and that DO-160 is designed to cover load dump and the
equipment actually was tested to that specific part of DO-160. Quite a leap
of faith in my opinion but perhaps not, as only the test results will tell.
It is important to emphasize that damaging Load dumps need very special
conditions to occur. Turning off your landing lights produces a load dump
but a non failed system clamps it to harmless levels.
There are several different tests needed, starting with components,
assemblies, and ending up with system tests from alternator to battery with
simulated (resistive) equipment loads.
Voltage, current, and waveform recordings are included as needed in several
parts of the system.
The initial test demonstrated very repeatable results and verified the
instrumentation approach.
The testing is on a very limited set of major components. I do not have the
$$ and time to test lots of components costing $$ each. TVS devices I do
have in quantity in various types, but alternators and contactors are a
different matter.
I do not consider this a problem however, as any solution must have a design
margin "Built in" of several times the measured data to cover major part
variations.
I am dismayed at the many recent comments, all apparently based on
conjecture (at least I have not seen ANY reference to ANY real data) based
on literature and concepts that have widely different conditions assumed.
Looking thru the various data sheets and application notes provides a
surprising array of examples of simulated load dumps and general comments
and NO real alternator test load dump data. Lots of opinions presented as
facts to support the authors opinion.
I do not plan on any further comments on other load dump posts/comments
until the testing is completed as to date its simply an exchange of opinion
with no facts and takes time and bandwidth.
As to comments that DO-160 equipment being designed to survive any load dump
on any aircraft; I question that, but not having the relevant DO-160 test
requirements, I have no way to comment.
Paul
Message 6
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| Subject: | Re: Co-ax splice method |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 11:10 PM 5/13/2004 -0700, you wrote:
>--> AeroElectric-List message posted by: "KeithHallsten"
><KeithHallsten@quiknet.com>
>
>I'm about to close up the winglets on the Velocity I'm building, and I
>need to extend the antenna wire first. The copper-foil type antenna came
>to me with a short length of RG-58 attached, already glassed into the
>winglet. I intend to extend it to the instrument panel with RG-400. The
>area where the splice will be made will be inaccessible once I seal up the
>winglet, so I want to use the parts and technique that has the lowest
>probability of a problem for the life of the airframe. I could just
>install a male connector on one and a female connector on the other, then
>mate them and cover with some heatshrink. Is this the best approach to
>this situation? Thanks for your advice!
That's what I'd do. There is another suggestion for covering the joint with
silicone tape. See S894 at bottom of page at:
http://bandc.biz/cgi-bin/ez-catalog/cat_display.cgi?9X358218#S894
This tape is not very robust mechanically so I'd put a layer of
heat shrink over it. You don't need much tape . . . one layer
stretched tight and 30-50% overlap on turns is sufficient.
Alternatively, there are internal melting wall heatshrinks
that seal and encapsulate the finished joint.
Bob . . .
Message 7
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| Subject: | Re: For Bob Nuckolls: Roll your own |
crowbar module troubles
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
crowbar module troubles
At 10:09 PM 5/13/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: Ralph Ketter
>
>Bob,
>This is a resend of previous information I posted but you didn't get.
Peter, sorry for the delay on responding to this. Had a really
busy week. I've printed your values out. Got a really boring
meeting to go to this afternoon. I'll noodle over the data
then.
Bob . . .
>I build my own OV crowbar module and it functions correctly except that
>it operated in the 10-11 volt range. I triple checked the components
>and wiring. I changed the 1.62K ohm resistor specified for a 14 volt
>system to 6.04K and the circuit operates in the correct voltage range of
>15.5-17 volts.
>***************************
>Designating Point (1) as the + end of the capacitor, and Point (2) as the
>junction of the 392 ohm resistor, and GND as the negative lead, with the
>pot at midrange I got the
>following readings:
>******
>1.62 K resistor in place for 14 volt operation. - Trip point = 10.4
>volts.
>Point (1) - Point (2) +0.436 volts
>GND - Point (2) +7.6 volts
>******
>6.04K resistor replacing the 1.62K one. - Trip point = 16.22 volts.
>Point (1) - Point (2) +0.538 volts
>GND - Point (2) +7.36 volts
>******
>
>These readings made me realize the circuit was not letting the zener
>regulate at 12 volts so I did the following checks.
>First I disconnected the SCR trigger lead to prevent it from firing. I
>reinstalled the original 1.62K resistor.
>
>Measuring the Zener voltage from GND to Point (2):
>As I increased the input voltage the voltage across the zener increases
>linearly to about 8.25 volts and then starts to decrease. The input
>voltage is about 9 volts when this knee occurs.
>
>I then disconnected the 1N4148 diode and repeated the above test with
>basically the same results.
>
>With the 1N4148 diode still disconnected, I also disconnected the NPN
>collector and PNP base (they remained connected together) from the point
>(2) junction. Now only the Zener and 392 ohm resistor are in series
>across the supply. Again measuring the Zener voltage from GND to point
>(2):
>The zener voltage tracks the input voltage up to about 11.3 volts at
>which point the zener begins to regulate.
>
>With the two transistors still disconnected, I reconnected the 1N4148
>diode.
>Now the voltage across the zener increases linearly up to 9 volts (input
>voltage is 9.35) when suddenly the voltage drops to 1.87 volts.
>
>Do you have any suggestions to help troubleshoot of fix it.
>
>Ralph Ketter
>RV-6
>Marysville, KS
>***************************
>
>
Bob . . .
-----------------------------------------
( Experience and common sense cannot be )
( replaced with policy and procedures. )
( R. L. Nuckolls III )
-----------------------------------------
Message 8
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--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 07:13 AM 5/14/2004 -0700, you wrote:
>--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
>
>Bob,
>
>I would like to know the DO-160 requirements associated with transients
>above say 24V including pulse duration, shape and peak V where the duration
>is under one second.
>
>For example I recall there is a 40V pulse but I do not know its duration or
>shape. I seem to recall there is a longer pulse at a lower voltage also.
>Then there is the maximum Voltage steady state level. And perhaps others
>addressing above normal bus voltage ranges.
>
>This info will help me with the load dump testing. Specifically IF I find
>what appears to be a condition that exceeds DO-160 requirements. In that
>case I want to further analize the test results and it would also be a
>factor in any proposed solution which would be a final part of the load dump
>tests.
>
>Paul
Do you have a fax machine. I'll send you sections 16 and 17 out
of the book. I could scan and e-mail them if needs be but it would
be a huge file.
Bob . . .
Message 9
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--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
Your off line response was great thanks a lot.
Paul
-----
>
> Do you have a fax machine. I'll send you sections 16 and 17 out
> of the book. I could scan and e-mail them if needs be but it would
> be a huge file.
>
> Bob . . .
>
Message 10
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| Subject: | re: LOAD DUMP TEST START |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 07:02 AM 5/14/2004 -0700, you wrote:
>--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
>
>The long waited REAL testing started on 5-13-04.
>
>This will take as long as it takes :-) at a rate of a couple of hours per
>day, but likely completed this month. (Could also be less than a week to
>preliminary final results, full writeup/documentation may take months.)
>
>Its not simple to design a test of this complexity when the results will
>subject to the likes of Bob :-). I have some preconsived ideas of the
>results (as do many of us, including Bob, but have set that aside and will
>let the results stand for themselves. The test conditions are designed to
>allow others to duplicate with reasonable accuract what I am doing so any or
>all parts can be setuip in a different lab and the results should be
>comparable considering the component and test equipment variations.
>
>System level Load Dump is not a simple issue as some have tried to make it.
>That is IF the objective is to detail what happens and how it can effect the
>other parts of the system. Even the OVP module is part of the system during
>the time it takes to open the associated 5 amp CB.
>
>Only protection of the alternator internal diodes and regulator is one
>solution and that only takes clamping the voltage to 35-40 volts and that
>voltage is way too high for some equipment including some of mine.
>
>Others will accept the above as enough and TRUST the rest of their system
>meets DO-160 and that DO-160 is designed to cover load dump and the
>equipment actually was tested to that specific part of DO-160. Quite a leap
>of faith in my opinion but perhaps not, as only the test results will tell.
Anyone who produces a product (not a distributor or dealer) should
be expected to KNOW the capabilities of their product. If they
beg ignorance in matters of input power variability, then their
skills in other matters of the product design are suspect as well.
>It is important to emphasize that damaging Load dumps need very special
>conditions to occur. Turning off your landing lights produces a load dump
>but a non failed system clamps it to harmless levels.
>
>There are several different tests needed, starting with components,
>assemblies, and ending up with system tests from alternator to battery with
>simulated (resistive) equipment loads.
>
>Voltage, current, and waveform recordings are included as needed in several
>parts of the system.
>
>The initial test demonstrated very repeatable results and verified the
>instrumentation approach.
>
>The testing is on a very limited set of major components. I do not have the
>$$ and time to test lots of components costing $$ each. TVS devices I do
>have in quantity in various types, but alternators and contactors are a
>diferrent matter.
My mental image derived from your words suggest the task
you describe is more complicated than it needs to be.
I don't see much value in knowing the middle ground values
for load dump events. We know what produces the worst case and
we know that some manner of energy sink is needed to
grunt the overshoot. See:
http://www.aeroelectric.com/temp/loaddumptest.jpg
This setup would allow one to take a commercial off-the-shelf
alternator (I'd use a new N-D from B&C) or any number of junk-yard
takeoffs to plot characteristics of the load dump event as it
relates to load and speed of the alternator. You'd have to start
out slow and low and work your way up to the conditions that
ultimately trash the alternator's built in regulator. Alternatively,
once the speed/load conditions are identified that put the regulator
at risk (something on the order of 40v) then one could switch
to investigation of proposed TVS devices to stand off the load-dump
event up to and including full load on alternator at 12,000 rpm.
By limiting unprotected testing conditions to those which do not
produce regulator killing spikes, one could shift attention to
the protection investigation at little risk for needing to repair
a test article. A data acquisition system or recording 'scope could
capture the voltage/current characteristics of energy dissipated
in the TVS during load-dump events.
It's would be interesting to explore ALL the variables associated
with the various hypothetical situations it seems that the most
economical effort is to size the device needed to clamp the
worst case scenario at whatever target voltage you choose
<snip>
>I do not plan on any further comments on other load dump posts/comments
>until the testing is completed as to date its simply an exchange of opinion
>with no facts and takes time and bandwidth.
>
>As to comments that DO-160 equipment being designed to survive any load dump
>on any aircraft; I question that, but not having the relevant DO-160 test
>requirements, I have no way to comment.
I have made the full text of DO-160 available to you. I cannot speak
to the thinking of committee members while this document was being
crafted. Don't know if they were considering alternators, generators
or both but the values speak for themselves.
See paragraph 16.5.4.4 where the worst case (Category Z) for 28v
systems cites 80v square pulse (figure 16-4) for 100 milliseconds.
and 48 volts for 1 second. This test is intended to characterize
resistance to a spectrum of surge voltages described in Figure 16-6.
14V system values are 1/2 the 28v system voltages but with the
same times so 40 and 24 volt surges apply. I've been testing
to these values for over 30 years . . . it's a no-brainer.
It seems to me that selection of a TVS device for clamping
alternator load dumps to values LESS than those described
in the first 100 milliseconds of figure 16-6 is no big deal.
The OVP system takes care of lower voltage events beyond
100 milliseconds.
This presumes, of course, that suppliers take the time and
effort to recognize the value in building voltage surge
immunity into their products as suggested by DO-160.
If one wishes to limit load-dump amplitudes to values
lower than those suggested by DO-160, then it's simply a
engineering and parts selection task with new bounds.
With a limited budget for time and dollars, it seems
prudent to limit the investigation to conditions specific
to the worst case.
Bob . . .
Message 11
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| Subject: | FS - EGT/CHT probes |
--> AeroElectric-List message posted by: richard@riley.net
I've got 6 each Grand Rapids Technology EGT and CHT probes that I should
get rid of - they're extras and have never been installed or used. Hose
clamp style EGT, bayonet style CHT.
They're $444 new, I'll sell the lot for $350. I'd prefer to sell the whole lot.
Message 12
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| Subject: | Re: re: LOAD DUMP TEST START |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
----- Original Message -----
From: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Subject: AeroElectric-List: re: LOAD DUMP TEST START
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<bob.nuckolls@cox.net>
>
> At 07:02 AM 5/14/2004 -0700, you wrote:
> >--> AeroElectric-List message posted by: "Paul Messinger"
<paulm@olypen.com>
> >
> >The long waited REAL testing started on 5-13-04.
> >
>>
> Anyone who produces a product (not a distributor or dealer) should
> be expected to KNOW the capabilities of their product. If they
> beg ignorance in matters of input power variability, then their
> skills in other matters of the product design are suspect as well.
Agreed but then I have found many who seem to know about DO-160 and yet seem
to have other product design problems. Also its very hard if not impossible
to get thru sales to engineering to determine if the 24V max input V has
margin including passage of a specific DO-160 by test or just engineering
analysis or wishful thinking.
Expect and assume are not something I use frequently as its poor thinking in
far too many cases.
>
>
> My mental image derived from your words suggest the task
> you describe is more complicated than it needs to be.
> I don't see much value in knowing the middle ground values
> for load dump events. We know what produces the worst case and
> we know that some manner of energy sink is needed to
> grunt the overshoot. See:
>
> http://www.aeroelectric.com/temp/loaddumptest.jpg
Interesting but seems to not address what happens before the "B" lead
contactor opens to the equipment on the busses.
> This setup would allow one to take a commercial off-the-shelf
> alternator (I'd use a new N-D from B&C) or any number of junk-yard
> takeoffs to plot characteristics of the load dump event as it
> relates to load and speed of the alternator.
I do not have a B&C or a ND alternator and no reason to know that its
nominal much less worst case with regard to load dump. Thus the need for any
test results to have design margin added.
As for the DO-160 your info will be of great value to me during this testing
period and far beyond.
This is a low budget test and I do not have either the time or money to get
fancy with variable speed drives, specific alternators, and extensive
testing. I am not convinced there is all that much difference in alternators
with similar current ratings. I do have a 45 and 65 amp (different brands
and neither ND) alternator to test so we will see. I am testing what my
background and education suggest needs to be tested.
However one main concern is how a major load dump interacts in an aircraft
system considering internal and external regulators and "B" lead contactors
as well as battery contactors and the OVP interaction during the initial
part of the load dump before the OVP blows the fuse starting the "B" lead
contactor disconnect etc.
> By limiting unprotected testing conditions to those which do not
> produce regulator killing spikes, one could shift attention to
> the protection investigation at little risk for needing to repair
> a test article. A data acquisition system or recording 'scope could
> capture the voltage/current characteristics of energy dissipated
> in the TVS during load-dump events.
That is what I have here A digital storage computing O' scope including the
built in waveform computer for calculations etc. The delays were in part
getting an expensive recal of the equipment for free (IE in spare time at
test lab).
Paul
Message 13
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| Subject: | Antenna Placement |
--> AeroElectric-List message posted by: "Ross Mickey" <rmickey@ix.netcom.com>
-----Original Message-----
On Behalf Of Nielsen Mark
Subject: AeroElectric-List: Antenna Placement
Bob and Others,
2. Another option would be to mount the NAV antenna on the bottom of
the
fuselage. The balun would be attached directly to the bottom of the
fuselage with the whiskers a 1/2" or so below the skin. How would this
work?
This is how mine is set up. The whiskers are under the horizontal.
This setup works great.
3. If the NAV antenna is installed on the bottom of the fuselage, how
far
must (should) it be away from the COMM antenna?
My com is located just aft of the battery box of my 6A on the
centerline. There is no interference with the Nav. I am going to
install a second Com behind the first that will be closer to the Nav. I
will report after this is tested.
Ross Mickey
N9PT
RV6A
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