Today's Message Index:
----------------------
1. 05:58 AM - SD-8 and meltdowns (Matt Jurotich)
2. 06:53 PM - Re: Re: OV protection for internally regulated alternators (John Livingston)
3. 07:21 PM - trick for combing out shield? (Dan Checkoway)
4. 08:02 PM - My Jabiru J400 made test flights, (Scott, Ian)
5. 08:09 PM - Fw: RV-List: Re: Dynon EMI (different scenario) (David Carter)
6. 08:10 PM - Re: DIY audio amp (Robert L. Nuckolls, III)
7. 08:11 PM - Re: SD-8 and meltdowns (Robert L. Nuckolls, III)
Message 1
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| Subject: | SD-8 and meltdowns |
--> AeroElectric-List message posted by: Matt Jurotich <mjurotich@hst.nasa.gov>
Bob and All
I have been watching for the story on the SD-8 and meltdown of the external
regulator. Did I miss it or we don't have info yet? I thought Bob said he
was going to do some experiments.
Thanks
Matthew M. Jurotich
NASA/Goddard Space Flight Center
Swales contractor to the
JWST ISIM Systems Engineer
m/c : 443
e-mail mail to: <mjurotich@hst.nasa.gov>
phone : 301-286-5919
fax : 301-286-1736
JWST URL: <http://ngst1.gsfc.nasa.gov
Message 2
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| Subject: | Re: RE: OV protection for internally regulated alternators |
--> AeroElectric-List message posted by: "John Livingston" <livingjw@earthlink.net>
Bob,
If I have a progressive battery/alternator switch can I still get into
trouble if I quickly slam it totally off instead of taking the alternator
off line, pause then turn off the battery? I can see how this might happen
during an incident, if, for instance, one smelled smoke in the cockpit. Is
this one senerio of concern?
John
----- Original Message -----
From: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Subject: AeroElectric-List: RE: OV protection for internally regulated
alternators
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<bob.nuckolls@cox.net>
>
> As promised, I've been looking into this problem and I've crafted
> a white paper on the topic. Here is the text of the paper . . .
>
> -------------------------------------------
> "Load Dump" Damage to Alternators with Built-in Regulators
>
> Bob Nuckolls
> 1 February 2004
>
> >AeroElectric-List message posted by: "Ned Thomas" <315@cox.net>
> >
> >For what it is worth, I had an internally regulated alternator
> >on my RV6A. I had an overvoltage occur and had no way to
> >shut it off except land and turn off the engine. When
> >I smelled the battery acid cooking out I was quite concerned.
> >I was able to land before ruining the battery but even tho
> >I immediately turned off the master when I found the
> >voltmeter reading high, I did find that one of my strobes
> >had fried. After this happened I installed the OV protection
> >recommended by Bob. In the event you do encounter an OV
> >situation you must be able to isolate the alternator.
> >I was lucky, the battery could have blown up...
>
> >----- Original Message -----
> >From: "Clay R" <clayr_55@yahoo.com>
>
> >Now I see the following warning on Vans web site on
> >the alternator page. (I think this was added this week)
>
> >Warning!
>
> >The internally regulated 60 ampere alternator should not
> >be used with overvoltage protection systems. If you
> >open the charging circuit while it is in operation,
> >it will destroy the regulator.
>
> >AeroElectric-List message posted by: "Steve Sampson"
> <SSampson.SLN21@london.edu>
>
> Clay - is anyone looking into this for you? It sounds
> >like plenty of people are getting blown alternators
> >after putting the B&C stuff on.
>
> BACKGROUND
>
> (1) The "B&C stuff" is only a collection of parts described in documents
> described in the AeroElectric Connection. Let us take care as to how the
> phenomenon is described with respect to implied cause and effect. It's not
> B&C's architecture but AeroElectric Connection architecture . . . B&C only
> sells the parts to implement it.
>
> (2) For years and since day-one of my participation in B&C's development
> and marketing of alternators, we have preached the doctrine of externally
> regulated alternators. Examples of this philosophy are found throughout
> early writings and particularly in chapters on alternators and regulators
> in the 'Connection. A simple inspection of B&C's offerings from the
> beginning will show that only externally regulated alternators are
offered.
>
> (3) There has been a lot of interest in adapting internally regulated
> alternators to aircraft because they are so readily available and cheap.
> Further, they've produced an excellent track record of reliability on cars
> . . . it seems a shame not exploit that characteristic in aircraft.
>
> (4) The challenge for adapting internally regulated alternators to
> airplanes has always been making them behave like externally regulated
> alternators and generators before them. On the instrument panel there is a
> switch labeled ALT OFF/ON. One expects that operation of this switch will
> produce the same result whether you're sitting in a 1965 C-172 or a 2004
RV-8.
>
> (5) Most alternators with built in regulators, once given the ON command
> via the rear-connected control wire will indeed come alive . . . but since
> this wire was originally intended only as a means for the EFI controller
on
> a car to delay onset of engine loads after starting, there was no
> requirement for being able to turn the alternator OFF via this same wire.
> So, the vast majority of automotive take-offs cannot be turned OFF by
> removing +14v from the control wire via panel mounted switch. This
> condition was experienced by Mr. Thomas in the anecdote cited earlier.
>
> (6) While the probability of regulator failure in cars is exceedingly low,
> it is not zero. We've heard anecdotal stories of unhappy, high-dollar
> events taking place in airplanes after failure of an internally regulated
> alternator.
>
> (7) With the goal of addressing a desire in the marketplace to utilize
> off-the-car technology, figure Z-24 was developed to address both
> controllability and overvoltage issues with the lowest practical parts
> count and without modifying the alternator.
>
> RECENT HISTORY
>
> It seems that there have been a rash of failures of internally regulated
> alternators installed per Figure Z-24. Let's review the inner workings and
> shortcomings of the modern, internally regulated alternators. We know that
> all alternators run best with a battery connected across their output. The
> battery is an excellent filter for the noise inherent on DC power
generated
> by rectified 3-phase AC power. The battery also provides a flywheel
effect
> . . . a kind of electrical inertia that damps out the frisky nature of an
> alternator's ability to quicky respond to and control its own output.
>
> A phenomenon labeled by the automotive industry as "load dump" speaks to a
> characteristic native to the physics of alternator performance. Its
> existence has been known since the beginnings of alternator use in
> vehicles . . . but it was only a concern after a proliferation of solid
> state electronics for fuel injection systems, ignition systems, anti-lock
> brakes, etc. Should an alternator producing a lot of power be suddenly
> disconnected from the load, it may generate what would be properly called
a
> surge of voltage exceeding bus voltage by several times. If the load dump
> is limited to shedding of normal system loads, the battery's electrical
> inertia will be in place to smooth over the event. However, if the
> disconnection includes the battery, no mitigating electrical-mass is
> present to capture a significant energy transient. In aviation parlance,
> a "load dump" is rapid shedding of normal system loads. The scenario we
are
> discussing might be more appropriately called a "battery dump".
>
> Unlike relatively low energy spikes characteristic of switching transients
> on inductive loads, a battery dump event is longer and carries a lot more
> energy. In the spring of 1998, there was a romance in the OBAM aircraft
> community with products called transient voltage suppressors (TVS). A
> school of thought suggested that the electrical system be sprinkled with
> these little critters to ward off effects of any gremlins of the
> overvoltage persuasion which may be lurking about the system. The
suggested
> technique was to install a TVS on the power feeder for each vulnerable
> accessory.
>
> There was an extensive discussion thread. You may review published
excerpts
> of that discussion at:
>
> http://aeroelectric.com/articles/spike.pdf
>
> This was before we began to consider and refine any notions of using
> internally regulated alternators in OBAM aircraft.
>
> In that thread, I suggested it was much better to (1) identify and
mitigate
> such hazards at their source and/or (2) design accessories to be immune to
> such hazards. For decades, DO-160 has been an effective guideline for
> development of robust victims while MIL-STD-704 outlined design goals for
> output quality of power generation equipment.
>
> Here are but a few of hundreds of relevant documents on the phenomenon to
> be found on the web . . .
>
> http://www.sto-p.com/pfp/pfp-transients.htm
>
> http://www.onsemi.com/pub/Collateral/CS3341-D.PDF
>
> http://www.audifans.com/archives/1998/08/msg00929.html
>
> . . . do a Google search on "load dump" and "alternator" for a wealth of
> useful expansion of the topic.
>
> WHAT'S HAPPENING?
>
> The original discussions 4 years ago focused on the need to protect system
> accessories from the effects of alternator behavior. In the cases before
us
> now, the victim is NOT airframe system accessories being hammered by a
> skittish alternator. These are cases where the alternator is killing
itself
> . . . or more accurately, killing its own voltage regulator.
>
> If you look over the specifications for modern, solid state regulator
> chips, you'll find references to protection against load dump conditions
> built right onto the chip. I believe what we're observing now is a
> shortcoming of relatively mature automotive take-off alternators with
> regulators that do not enjoy this kind of protection.
>
> Referring to the group of block diagrams in this document, note that I've
> illustrated 4 configurations of installation architecture for alternators
> with built in regulators.
>
> (download
>
> http://www.aeroelectric.com/articles/Alternator_Failures.pdf
>
> to get the illustration)
>
> (1) The first diagram is captioned "AUTOMOTIVE" and it illustrates the
> relationship between battery and alternator in virtually all automotive
> applications. The battery is ALWAYS connected to the alternator. System
> loads are controlled via panel switches and/or ignition switch but
portions
> of the power distribution system are always hot, even when the vehicle is
> parked. Not desirable on airplanes.
>
> (2) The second configuration is "FIGURE Z-24" referring to an architecture
> described in the AeroElectric Connection to accommodate two hard-and-fast
> design goals for using an alternator in an airplane: (a) absolute control
> of the alternator operation from the cockpit irrespective of flight
> condition and (b) protection against the very rare but potentially
> hazardous and expensive overvoltage condition.
>
> (3) The third configuration describes an ill-conceived recommendation
> suggesting deletion of the alternator disconnect and wiring the
alternator
> to the airplane a-la-automotive. Note that while this configuration
> prevents the pilot from switching an alternator off while in operation,
it
> does not prevent the battery from being taken off line. If we
> disconnect the alternator from the system while leaving the battery on
as
> allowed with Figure Z-24, only the alternator is at-risk for self
destruction.
>
> When you leave the alternator connected to the system and shut off the
> battery master, there is still risk of a battery-dump transient. While
> system loads will soak up some transient energy and mitigate amplitude and
> duration of the event, now the whole system is subjected to the transient.
>
> In airplanes like the Baron and Bonanza where alternators and battery
> master switches are separate, non-interlocked controls, switches can be
> manipulated in a manner that will produce the same "battery dump" effect
> that we're discussing. So the potential for this effect is not new nor is
> it unique to the nifty little alternators so popular in the OBAM aircraft
> community.
>
> (4) The fourth configuration illustrates an experiment to be conducted
> which may prove the usefulness of a technique intended to tame the dragon.
>
> A PROPOSED GAME PLAN
>
> (1) If you have Figure Z-24 installed and you're already flying or nearly
> ready to fly, don't change anything. Although you may never need the
> protections Z-24 offers, I don't recommend you go flying without it. It
is
> EASY to prevent battery dump damage to the alternator by controlling
> sequence of operation for the switches.
>
> [a] Battery master is the first switch to come on before cranking the
> engine and it should stay on until after engine shutdown.
>
> [b] The alternator control switch may be turned on before cranking the
> engine but it's probably better to leave it off until after the engine is
> running.
>
> [c] At the end of the flight, shut the engine down before first turning
> off the alternator . . . .
>
> [d] . . . followed by turning of the battery master switch.
>
> Following suggestions in any of the Z-figures in the 'Connection will
> provide you with interlocked battery master and alternator control
switches
> wired so as to prevent an alternator from remaining on-line with the
> battery disconnected.
>
> The battery dump transient is generated by the disconnection of the
battery
> from the alternator b-lead terminal while the alternator is working hard.
> It can't be working hard if the engine is not running. The warning
> published by Van's is accurate as far as it goes but misses important
> points with respect to absolute operational control of the alternator from
> the cockpit and overvoltage protection. So, if you don't diddle with the
> switch while the engine is running, your alternator is not at risk for
> battery dump damage and you retain both operational control and
overvoltage
> protection.
>
> (2) If you have yet to select an alternator but need to do it soon, you
> cannot go wrong with installing an alternator designed for aircraft
> service. Alternators using external regulation are easily managed for both
> operational control and overvoltage protection by simply opening the field
> lead. This activity does not generate the battery dump transient we're
> discussing.
>
> (3) I'm planning to test an alternator with built in regulation on a test
> stand using a fat TVS device connected as shown in the last block diagram.
> I'll be making measurements of worst-case transient energies and making
> sure that the diode we select is adequately sized to the task.
>
> NOTE
>
> If anyone out there remembers the zener diode
> that Pelican Aviation used to stick on the back
> side of their alternators (some STC'd no less!)
> while calling it "overvoltage protection" please
> recall that this was neither ov protection nor
> was it a practical solution to the problem
> before us now.
>
> After the bench testing studies are complete, I'll be looking for
> volunteers who are already flying Figure Z-24 alternator control schemes.
I
> will supply a pair of TVS diodes for installation on your airplane. You
> will be asked to conduct a series of battery dump simulations. After the
> simulations, you'll be asked to install the second diode and return the
> first one to me for inspection.
>
> Once we've done the repeatable experiment to demonstrate suitability of
the
> "fix", this paper will be updated to publish the results and Figure Z-24
> will be updated appropriately. In the mean time, I'll supply a copy of
this
> paper to Van's in with the hope that it will clarify the issues and
> forestall some poorly founded modifications to electrical systems in the
> OBAM aircraft community. Please feel free to circulate this document for
> both its informative value and potential for critical review.
>
> As a closing note to this document, I ran across this paper:
>
> http://www.st.com/stonline/books/pdf/docs/4345.pdf
>
> . . . written by the folks at SGS-Thompson on battery dump mitigation.
This
> paper describes a proposed technique for building battery dump management
> right into the alternator . . . what a concept! Whether or not this
> capability will be offered in automotive products suited to airplanes soon
> is hard to predict. In the meantime, it's a no-brainer to make the
> alternators we have work quite nicely.
>
> The bottom line folks . . . I believe there is good value in the use of
> internally regulated alternators on airplanes. However, it's important
that
> we make decisions based upon good science that helps us understand and
> accommodate their unique characteristics.
>
> Bob . . .
>
>
Message 3
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| Subject: | trick for combing out shield? |
--> AeroElectric-List message posted by: "Dan Checkoway" <dan@rvproject.com>
Is there any slick trick for combing out braided shielding more easily?
Case in point, RG-400 with its double layer of shielding.
)_( Dan
RV-7 N714D
http://www.rvproject.com
Message 4
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| Subject: | My Jabiru J400 made test flights, |
--> AeroElectric-List message posted by: "Scott, Ian" <ian_scott@commander.com>
Last Sunday the my Jabiru J400 did its first test flight and a subsequent flight
of a few hours, all was good, and all the smoke stayed in the wires.
Elevated CHT due to the new engine, all the rest good and nearly 2000Fpm climb,
man this is a rocket.
Ian
Message 5
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| Subject: | Fw: RV-List: RE: Dynon EMI (different scenario) |
--> AeroElectric-List message posted by: "David Carter" <dcarter@datarecall.net>
This interesting thread on the RV-list probaly has a place on the
Aeroelectric list, also, in case some players aren't monitoring both.
David
----- Original Message -----
From: "Kevin Behrent" <kbehrent@cascadiasoftware.com>
Subject: Re: RV-List: RE: Dynon EMI (different scenario)
> --> RV-List message posted by: Kevin Behrent
<kbehrent@cascadiasoftware.com>
>
> "Paul Boyce, Ph.D." wrote:
>
> > --> RV-List message posted by: "Paul Boyce, Ph.D."
<matronicspost@csg-i.com>
> >
> > There's a couple of very disappointing things about this situation:
> >
> > 1) in a total electric failure emergency, my backup handheld radio will
most
> > likely be rendered useless.
> >
> > 2) in an otherwise excellent product, those engineering folks at Dynon
have
> > completely dropped the ball in not doing thorough Quality Control checks
on
> > EMI. Isn't it obvious that in a highly electrified environment such as
an
> > airplane cockpit, one MUST check for EMI? Is that too much to ask?
> >
> > I will be giving them a call tomorrow.
> >
> > Paul
> >
>
> One possible reason why some people are having "noticeable" EMI
interference
> and others don't is the quaility and vintage of radio(s) that they have
> installed.
>
> I say this because I have experienced this when I had a complete panel
upgrade
> on my Mooney where a complete Garmin stack was put in, but I retained my
old,
> trusty, Narco Mark 12D+/DME. The GNS430 and the Narco constantly
interfered with
> each other and both units were sent back to the respective factory on
multiple
> occassions. What was finally determined, by both manufactures, was noise
> filtering capability on both units. The 430 does a pretty good in pre/post
> filtering so that the large LCD panel would not interfere with "newer"
avionics.
> The Narco, on the other hand, has little pre filtering, thus is very
reactive to
> the lcd screen. It also emits it's own share of emi that the 430 tries to
> handle, but fails when conditions are right. The solution, however
exceptable
> but not perfect, was shielding everything, and doing some rework on the
radio
> trays to help shield.
>
> The lesson I learned was not to mix new new with old. For what it cost to
> minimize the problem, I could have purchased a second 430.
>
> We had the President of Dynon speak at our January EAA monthly meeting and
I can
> say that he and his engineers are very bright people and they will find a
way to
> reduce or eliminate the problem. On the other hand, LCD screens will
always
> emit a certain level of radiation that older generation of radios do not
> filter. As glass panels evolve, so does radio filtering. However, don't
expect
> that your radio(s) are properly filtered to guard againt these emissions.
>
> It would be interesting to study the type of avionics being used by both
groups
> and see if there are any similarities.
>
>
> Kevin Behrent
> RV-9A - Wings
> EAA 326, President
>
>
Message 6
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| Subject: | Re: DIY audio amp |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 02:22 PM 2/1/2004 -0500, you wrote:
>Bob:
>
>I am building your stereo audio mixer and had questions:
>
>http://www.aeroelectric.com/Catalog/AEC/9009/9009-700D.pdf
>
>The schematic shows resistor R101, 102, 108 but there are no places for
>them on the etched circuit board. Where do I put them?
>
>Where do the input resistors R104, 105, 106, 107 go? Do they go across the
>header jumpers?
Sorry to take so long to get back with you on this. Seems
revision D of the assembly document was missing a parts
locator figure. I've repaired the omission and published
revision E at:
http://www.aeroelectric.com/Catalog/AEC/9009/9009-700E.pdf
You are correct, those parts are on the header.
Bob . . .
-----------------------------------------
( Experience and common sense cannot be )
( replaced with policy and procedures. )
( R. L. Nuckolls III )
-----------------------------------------
Message 7
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| Subject: | Re: SD-8 and meltdowns |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 08:58 AM 2/2/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: Matt Jurotich
><mjurotich@hst.nasa.gov>
>
>Bob and All
>
>I have been watching for the story on the SD-8 and meltdown of the external
>regulator. Did I miss it or we don't have info yet? I thought Bob said he
>was going to do some experiments.
I've got the regulator in-hand . . . too many irons in
the fire to do the study this week. I'm getting ready
for the KC seminar next weekend.
Perhaps next week.
Bob . . .
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