Today's Message Index:
----------------------
1. 07:35 AM - Re: OVP, Alternators, and stuff (Eric M. Jones)
2. 07:43 AM - OVP crowbar false triggering (Thomas Johnson)
3. 08:31 AM - How to test the OV? (Stewart, Michael (ISS Atlanta))
4. 08:35 AM - Re: OVP, Alternators, and stuff (Robert L. Nuckolls, III)
5. 08:47 AM - Re: Re: A question on my crossbar (Robert L. Nuckolls, III)
6. 08:52 AM - Re: OVP crowbar false triggering (Robert L. Nuckolls, III)
7. 09:47 AM - Re: Auto Pilot Servo Ground wire ()
8. 09:50 AM - Re: Re: OVP, Alternators, and stuff (Mickey Coggins)
9. 11:33 AM - Re: Auto Pilot Servo Ground wire (Robert L. Nuckolls, III)
10. 11:33 AM - Re: Re: A question on my crossbar overvoltage (Ken)
11. 03:06 PM - Re: Re: OVP, Alternators, and stuff (plaurence@the-beach.net)
Message 1
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| Subject: | Re: OVP, Alternators, and stuff |
0.60 COMMA_SUBJECT Subject is like 'Re: FDSDS, this is a subject'
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
--> AeroElectric-List message posted by: Mickey Coggins
<mick-matronics@rv8.ch>
>> However, the Kilovac Czonka III P/N
>> EV200AAANA will do the job easily--200A Interrupt at 320V. As a bonus its
>> coil draws only 100 milliamps.
>Eric, are you saying this is the relay you recommend in this
>diagram: http://www.periheliondesign.com/OVP/OVschems.gif
>Mickey Coggins
Hi Mickey,
That's affirmative. I have a load of these for sale at $80 each (I
think...email me offlist). Nothing else I know is sure to do the job. My
approach is to eliminate all the other contactors anyway so this one is the
only one you need. When you consider it, the race car battery switches are
better than battery contactor; the starter contactor is only used to allow
the use of a wimpy ignition keyswitch; the ground power contactor is
unnecessary, and the crossfeed contactor can easily be eliminated (but I
have too much yardwork to do to describe the details....).
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
(508) 764-2072
When choosing between two evils, I always like to try the one I've never
tried before.
--Mae West
Message 2
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| Subject: | OVP crowbar false triggering |
--> AeroElectric-List message posted by: "Thomas Johnson" <trj01@comcast.net>
I would like to relate my experience with false triggering of the AEC OVP module.
When I started to check out my electrical system (prior to first engine start)
back in 2001, I saw a lot of false triggering. Many switches could invoke
this: fuel pump, flaps, wig-wag, strobes; sometimes switching on, other times
switching off, and there seemed to be a randomness to it.
The schematic for the AeroElectric OVP module has changed slightly over the years,
and I have built several versions. Each one displayed a unique personality
but all of them would false triggered under some condition. I experimented
a bit and eventually thought I "had it whipped" with an array of decoupling capacitors.
Once I moved on to engine start and flight testing I found that I still had a problem.
Engaging the starter almost always triggered the OVP, and in-flight flap
motor engagement sometimes did. For a while I just removed the OVP module
to get on with flight testing.
At some point I came across an AeroElectric-list post reporting a problem similar
to mine. E.Bob responded with a comment about the dv/dt condition that can
effect SCR devices and mentioned that he had considered re-designing the OVP
module using a MOS-FET instead of the SCR. I am an amateur EE and far more comfortable
with digital stuff than analog but I thought I would take a shot at
this.
I built an OVP module based on the IRL3803 and unfortunately the LTC1696. I say
unfortunate not because it is a bad part but that it made a bad experiment (changing
two things at once). I have been flying with this module for about a
year now and have not seen one false trigger. My guess is that there was nothing
wrong with the AEC OVP trigger and that this dv/dt thing was the heart of
my problems.
E.Bob has commented on several occasions is that he has seen this kind of nuisance
trip behavior before but that it is rare. Is there a way we can measure this
condition? I have it, but I have no idea what caused it.
Tom Johnson
Message 3
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| Subject: | How to test the OV? |
--> AeroElectric-List message posted by: "Stewart, Michael (ISS Atlanta)" <mstewart@iss.net>
How do I test my AEC OVP module? I have an internally regulated alt. and
the
I have searched the archives. And cant find the answer. I have the
pre-wired solenoid with the OV crowbar. S701-2
http://www.bandc.biz/S701-2.html
Thanks
Mike
Do not archive
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| Subject: | Re: OVP, Alternators, and stuff |
0.60 COMMA_SUBJECT Subject is like 'Re: FDSDS, this is a subject'
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 05:31 PM 7/14/2005 -0700, you wrote:
>--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
>
>BOB.
>
>I was not INFERRING anything I was QUOTING DIRECTLY FROM A MANUFACTURERS
>DATA SHEET and using the INDUSTRY STANDARD definitions for the terms used
>therein. No inference, no opinion, no weasel wording etc. Just simple facts.
My apologies. Can you give me a link to the specifications
for the parts you were investigating? Can you share your
thoughts for selecting those parts for consideration in the
study?
>I have seen CB specifications that do allow one time extremely high current
>breaking but the subject specification does not address any such terms.
>Also, in general, this hi current is one time only sacrificial use.
I'd be pleased to know what devices are so restricted and how
they might find their way into a builder's design.
>If the data sheet is in error it needs to be corrected. OPINION from
>engineers who build the devices (as you say "they've never even heard of any
>fault limits") do not trump the engineering REQUIREMENTS that we have in the
>aerospace industry that PREVENTS ANY violation of the manufacturers data
>sheet. Also the CB you used in your tests is not normally available to the
>general builders of OBAM aircraft. Clearly the Mil spec specifies fault
>limits but as below I cannot read what they are.
>
>I downloaded the mil spec data sheet and regardless of image processing its
>not possible for me to read any info relating to the test hi current trip
>currents but it appears to start with a 1xx current, clearly not hundreds of
>amps but that is a guess as its truly useless to read the specific page in
>the spec relating to this subject that you provided for our reading.
Oops. Stubbed my toe. The TESTS are described in 5806
but test LEVELS are called out in a detail spec for each part.
I've uploaded a typical detail spec for breakers used in Beechcraft
and RAC products for many decades past. See:
http://www.aeroelectric.com/Reference_Docs/Circuit_Breaker/MS3320.pdf
. . . specifically Table three where fault interruption test currents
in the thousands of amps are called out.
These qualification tests are described in the 5806 paragraph 4.7.14
Interrupting Capacity which you'll note was formerly called Rupture
Capacity. See also Figure 3 and Table VII. My gurus suggested that
the term "rupture" was abandoned because it conjured up visions of
an alternative meaning that implied explosion . . . which did happen
sometimes on high voltage, terrestrial power distribution systems
but never in vehicular systems. The term "interrupt" was thought more
appropriate. They didn't recall when this change was made but thought
it was more than 30 years ago. I could go dig the old specs out of the
microfilm and see but I'm not sure it's important.
>I guess we need to check our sources as when I called a CB mfgr the engineer
>I talked to said they would not recommend exceeding the limits on the spec
>sheet. Perhaps it's being conservative but as there is absolutely no reason
>for the hi current WHY?? have it?
But there IS/WAS a reason. When the crowbar ovp system was evolved, the
technology of choice was the relay . . . probably the poorest form of
mechanical
switch for interrupting a highly inductive circuit during an alternator
runaway event. I'll grant you that the crowbar technology is quite
dated . . . a malady that carries over from the certified world. When
we find something that works, it tends to be carved in stone in the
certified world. The LR series regulators are now over 20 years old
and some of those are certified too. I'm not arguing against new and
better ways to do things with today's parts. What I do object to
is general lambasting of an older technology as somehow evil, dangerous,
or lacking in good engineering consideration as a means for selling
the latest-and-greatest . . .
>I would like to hear from engineers that Designed the original breakers.
> From what I can find, none are still around and the current crop of
>engineers and reps lack of knowledge is understandable but clearly not a
>fact to rely on. Not useful to rely on "lack of info" as info in a
>discussion of FACTS. Consider this "latest version of the Mil spec is dated
>1967!"
Actually, that "1967" is "1987" for revision G which replaces revision
"F" dated 1972. But what does the date have to do with it? It's THE
specification to which every breaker we use in our aircraft is tested.
It wouldn't matter if it were crafted in 1940.
This includes all of the push-pull, miniature breakers offered by
Klixon, Cutler-Hammer, Mechanical Products, etc. I'll suggest the
real significance of the date shows the concept of high current
interruption capability is quite mature.
>I believe we should NEVER design by inference, opinion etc.. My aerospace
>experience says that parts are not necessarily the same quality.
My apologies again. I was looking at data sheets for the line
of breakers cited above where I could find NO prohibition for
expecting the breaker to perform as intended in the crowbar
OVP system. If data sheets you were referring to carried such
prohibitions . . . I'd be pleased to know which parts these are.
>Many times the coml testing is less and or the mil spec failed parts
>are redefined as commercial.
Except that there's no economic value in separate production
facilities for "commercial" and "military" components. Once the
design has been proven to be "qualifiable" into a military requirement,
then there's no economic advantage to build a lesser designed part
that's same as the military part except that it won't pass the tests.
Any of the manufacturers above will tell you that all parts of
a particular function and form factor are built on the same production
lines . . . just as the mil-spec integrated circuits were built on
the same lines as commercial parts. The only difference being the
screening and certification processes that required individual handling
of parts . . . the price of mil-spec parts has more to do with labor
intensive hoop jumping and paper shuffling than with any incremental
improvement in quality over it's commercial siblings.
The vast majority of suppliers to the mil-spec market have stopped
offering the screening services. If we want devices screened to
the mil-spec levels, we have to do it ourselves. Manufacturers
got tired of shuffling paper to "prove" that certain of their
every-day run of parts were suited to some customer's extra-ordinary
desires.
The manufacturers wanted to concentrate on building good parts
and get out of the paper business. We're more that welcome to
buy a bunch of their parts and generate a pile of paper to go
with them but we have to do that on our own.
>I am not aware of any requirements from you that specify the exact circuit
>breaker brand and style that also has an identical mil spec equivalent. Its
>extremely common for production lines to select parts for mil spec quality
>and the rest go to commercial usage (if there is a mil spec and commercial
>identical CB which is not always true.
Yes, when the manufacturer's were asked to produce mil-spec parts,
they would screen the output of a production line for parts that
were at the top of the bell curve for characteristics unique to
the military environment, usually things like operating temperature,
leakages, switching speeds, etc. When they found enough parts to
fill the mil-spec order, then parts that didn't meet the mil-specs
were probably sent through the commercial pipe. But a lot of parts
that WOULD meet mil-spec screening went through the commercial pipe
too.
>So, if your Crow Bar design depends on a specific mil spec equivalent CB you
>should so state that requirement. But WHY? as its so simple to limit the
>current with ONE low cost part and the debate and potential problem is
>history.
Because sir, if I capitulate to your suggestion in the spirit
of compromise and good will, then it's a tacit if not overt
acknowledgement of a design deficiency in thousands of delivered
systems. I belive that the "potential problem" does not exist
for reasons cited and DETAILED. If I believed that a critical
design deficiency exists, then I would be obligated to inform a lot of
customers about it and take remedial action.
The breakers we've always sold, recommended and supplied in our
kits have been the miniature, push-pull breakers from the
constellation of products offered by suppliers cited. I would
not expect other styles to be so different but if you can
cite them, I'll stand corrected as to interpretation of the
specs you examined. I'll acquire exemplar parts for examination
as to risks and go from there. Just tell me where to find them.
>Finally I posted how I got 400 amps thru your crow bar using normal wiring
>practices but different from your sample of one test that only shows one
>possible short current and ignores worst case possible design currents. You
>have apparently ignored the details of my 400 amp circuit that you can
>easily duplicate for your own edification.
I'll have to go back an look but I seem to recall we started
with a 700 amp value. The point of my bench experiments was to
put some more reasonable upper bound on expected fault currents.
Given that MY breakers of choice are all I-Squared*R devices and
have series heaters with resistances on the order of 40 milliohms
then the maximum zero-wire length fault current to be expected
is 500 amps. Add in some minimal wire lengths and add the 2v drop
across the triggered SCR and we get currents MUCH less than 500
amps; a small fraction of that to which MY choice of breakers was
qualified.
>MY circuit was not a wild example but an exact replica of what is in my
>aircraft. I did pick the CB for lowest resistance but the rest is a real
>duplicate with the actual batteries etc.
Which breaker? What wire lengths? Were these conditions chosen
as an optimization of a design or an investigation of the worst
possible case imaginable?
>Finally there is absolutely no reason for such a hi short current thru the
>crow bar when the addition of a simple resistor can correct this (to many of
>us, a glaring design fault) extremely hi current short.
100-200 amps for tens of milliseconds is a sneeze compared
to 200+ amps for seconds when cranking an engine. If we're
expecting electro-whizzies to operate in a graceful manner
during a 12,000 watt-second cranking event that happens
once-per-flight-cycle, then there's no reason I can deduce
to fear or demonize the 50 watt-second crowbar OV event that may never
happen over the lifetime of the airplane.
>I guess we need to check our sources as when I called a CB mfgr, the
>engineer I talked to said they would not recommend exceeding the limits on
>the spec sheet. Perhaps it's just being conservative ( I think its simply
>there is no testing to document out of spec conditions so its UNK as to the
>resulting conditions) but as there is clearly no reason for the hi current
>WHY have it?
>
>Please consider being accurate when quoting me. Its fine to disagree but as
>you often suggest just the facts so I resent being accused of false or
>misleading statements.
I presumed you were referring to the same data sheets I was
that described the style and quality of breakers common to
the certified aircraft industry. I'd be pleased to know what
breakers YOU were using and your rational for selecting those
devices to use in your tests. The interruption current limits
you cited must be INFERRED from the data sheets I was looking
at . . . please accept my apology and enlighten me as to the
data upon which you relied.
>Please consider running the test that I detailed to you (in a post to this
>list some months ago) that consistently produced 400 amp crow bar currents
>when 50 amps is an overkill to open the CB. These currents and the setup was
>done under lab conditions (and measured with quality lab calibrated
>equipment and while 400 amps was measured there was no worst case analysis
>to see what the real max current might be. I saw no reason to do further
>analysis as the basic design of the crow bar was unacceptable in my opinion
>and has a propensity to false trip (again in a repeatable lab environment,
>and You did agree with this in one of our past exchanges) and is another
>simple crow bar circuit design error that seldom is seen as its triggered by
>a uncommon set of circumstances but still should be corrected. I suspect
>this may be one source for the dozens of reported trips that have resulted
>in off this list removal of the device from aircraft. Both Eric and I have
>had many reports of this.
Yup, the SCR has sensitivities to dv/dt effects that must be
accommodated in the design of any product that uses them. First
crack at the design was compliant with everything MIL-Std-704
and DO-160 told us to expect. Experience from the field has
shown that there are unanticipated effects that dictated
refinement of the design. So what's new? The stand-by alternator
on the Bonanzas is a good example (Landing and taxi lights inrush
+ bounce of the breaker-switch would trip the system). That
system has been in successful service now for over 5 years and
has proven to been 1000% better than the system it replaced.
Overall, the system has enjoyed a good run in the marketplace
of better than 20 years. Problems have been identified and worked out
as soon as they were identified and are still being worked in
small numbers today. I hand-delivered a crowbar ovm to a customer
last night who is experiencing nuisance trips after add a new
transponder! We'll see if we can get an opportunity to deduce
root cause of this new phenomenon.
>Regardless I continue to be astounded that you have failed to simply add a
>simple resistor and limit the current to a reasonable value.
In our first designs (LR-1) there WAS a current limiting
resistor. It was a fabricated device that was labor intensive,
added to parts count and reduced reliability. Further testing
and investigation proved that it was UNNECESSARY and it was
removed in the LR-2 and subsequent designs.
>NO this not mean a return to posting but I will respond to what I feel are
>mistatements of my words.
Perhaps no mistakes at all. What we may be finally zeroing in on
is (1) an open exchange of all data upon which our designs and
assertions are based and and (2) a sifting design features for which you
say "Plan K" is "better" than "Plan F".
I have NEVER produced words intended to attack a new idea
or product. From my perspective, 100% of my efforts in this discussion
have been to defend the conception, design, fabrication, marketing,
refinement, and customer service for a product that has performed
as intended and without undue side-effects for about 30 years.
If you have a modern alternative to offer, nobody will be more
supportive than I . . . but as I write these words, we have
yet to benefit from any DATA supporting either (1) your demonization
of the crowbar ovp system in its present form or (2) demonstrations
of the next greatest thing offered to move our art and science
forward.
I feel like a guy selling vacuum tube radios that has somebody
standing on the sidewalk outside holding up a little black box
which just MIGHT be a transistor radio who is telling folks not
to buy my radios because they give you warts or trash your
brain cells. No, the little black box is not for sale, but that
will all happen "in due course." But in the mean time, if I
could be persuaded to change the color of the radio's case,
it would stop trashing brain cells and only cause warts.
Every endeavor starts out with what one hopes is an accurate
recipe for success. The recipe gets tweaked for improvements as
the market life of the product evolves. Any successful entrepreneur
welcomes suggestions for improvement. I have no illusions as to
the marketplace longevity of the crowbar ovp system. In fact,
I may even replace it myself. But please, let us evolve market
offerings based on shared information and science; not as
prophylactics against warts. I've laid out my recipe in detail
and offered DATA, repeatable experiments and marketplace history
to support that data. Any errors of inference on my part should
be easy to set aside and I'd be delighted to know the facts.
Bob . . .
Message 5
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| Subject: | Re: A question on my crossbar |
overvoltage protection
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
overvoltage protection
At 05:50 PM 7/14/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
>
>I wonder if this is related to what I reported a month or so ago?
>
>"While tracking down a electrical problem ( haven't run the engine yet)
>I was sidetracked for awhile by the circuit breaker that feeds a 40 amp
>OV relay on my permanent magnet alternator popping.
???? 40A breaker ???? What power distribution diagram are
you using?
> It seems that
>wiggling a loose connection between the breaker and the relay will trip
>the OVP and open the breaker. The crowbar OVP is constructed from the
>new design. It tests OK and it doesn't trip if the alternator switch is
>operated. It does trip if I intentionally rapidly connect and disconnect
>the wire to the relay. The relay coil draws about 130 mA. If I
>disconnect the OVP I am unable to make the C/B trip so it would seem
>that the OVP is activating. It doesn't seem to make any difference
>whether a diode is across the relay coil.
Hmmm . . .
>I'm guessing this is normal and I'm making voltage spikes at a faster
>rate than the OVP time delay resets but I would have expected negative
>spikes rather than positive spikes. "
It might be "normal" but not expected. I can deduce no
feature of the design that would "pump up" the ov protection
to some trip level based on the intermittent connection
you describe.
>At that time I also said that "temporarilly adding a unidirectional
>transorb across it makes it more resistant to tripping which seems to
>confirm that I am generating positive spikes" but in retrospect I'm not
>certain that the transorb made much difference. Since I can't cycle the
>switch fast enough to cause a problem and nobody commented, I tightened
>my loose connection and did not persue this further.
Interesting. I'm sorry I missed the original discussion. I presume
your talking about an OVM-14 from B&C. I've not had any activity
with that product for several years. I'd like to get yours back
to see if I can duplicate your experience on the bench. Shoot
me your address and I'll send you a new one and a return envelope
for the old one.
I'll remind everyone that I'm intently interested in pursuing
this kind of investigation on products of any manufacture and
if I don't pick up on the conversation from a routine List
posting, send me a direct e-mail through the website at:
http://www.aeroelectric.com/bob.nuckolls/ (I'm use this to
avoid posting the "real" address for 'bots' to find.)
I've got a lot of balls in the air at once and I don't
want folks to believe my inattention is an overt avoidance of
the issue.
Bob. . .
Message 6
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| Subject: | Re: OVP crowbar false triggering |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 07:42 AM 7/15/2005 -0700, you wrote:
>--> AeroElectric-List message posted by: "Thomas Johnson" <trj01@comcast.net>
>
>I would like to relate my experience with false triggering of the AEC OVP
>module. When I started to check out my electrical system (prior to first
>engine start) back in 2001, I saw a lot of false triggering. Many
>switches could invoke this: fuel pump, flaps, wig-wag, strobes; sometimes
>switching on, other times switching off, and there seemed to be a
>randomness to it.
>
>The schematic for the AeroElectric OVP module has changed slightly over
>the years, and I have built several versions. Each one displayed a unique
>personality but all of them would false triggered under some condition. I
>experimented a bit and eventually thought I "had it whipped" with an array
>of decoupling capacitors.
>
>Once I moved on to engine start and flight testing I found that I still
>had a problem. Engaging the starter almost always triggered the OVP, and
>in-flight flap motor engagement sometimes did. For a while I just removed
>the OVP module to get on with flight testing.
>
>At some point I came across an AeroElectric-list post reporting a problem
>similar to mine. E.Bob responded with a comment about the dv/dt condition
>that can effect SCR devices and mentioned that he had considered
>re-designing the OVP module using a MOS-FET instead of the SCR. I am an
>amateur EE and far more comfortable with digital stuff than analog but I
>thought I would take a shot at this.
>
>I built an OVP module based on the IRL3803 and unfortunately the
>LTC1696. I say unfortunate not because it is a bad part but that it made
>a bad experiment (changing two things at once). I have been flying with
>this module for about a year now and have not seen one false trigger. My
>guess is that there was nothing wrong with the AEC OVP trigger and that
>this dv/dt thing was the heart of my problems.
>
>E.Bob has commented on several occasions is that he has seen this kind of
>nuisance trip behavior before but that it is rare. Is there a way we can
>measure this condition? I have it, but I have no idea what caused it.
Great question and thanks for the post. Yes, the current
production ovp modules have been tweaked to accommodate
situations such as you've described. I would be delighted
to put my hands on your airplane with some test equipment
to see if we can understand why it's so different . . . or
whether the crowbar module has a manufacturing or design
problem.
Do you still have the old module? If so, you can send it
back to me for a no-charge upgrade. I'd be grateful to
hear of your experiences with the "upgraded" module. In
fact, since you have a "problem" airplane, it might
be interesting to send you several modules with various
evolutionary steps installed to see which one is the
"rose wood stake". If you're willing to participate
in the experiment, I think we could do some good science
here.
Bob . . .
Message 7
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| Subject: | Re: Auto Pilot Servo Ground wire |
--> AeroElectric-List message posted by: <chaztuna@adelphia.net>
---- "Robert L. Nuckolls wrote:
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
>
> At 02:16 PM 7/14/2005 -0400, you wrote:
>
> P.S. if you get a good answer from Trutrak, please
> share it with us on the list so that it gets stashed
> in the archives. Let us know who you talked, their
> phone number and what was advised along with any
> explanations they may have to offer.
>
> Bob . . .
Bob,
I spoke to tech support at Trutrak this morning. They told me to make all the
grounds at a single point.
Charlie Kuss
>
> >--> AeroElectric-List message posted by: <chaztuna@adelphia.net>
> >
> >Bob & Listers,
> > Should the servo ground wires for the Trutrak (or other) auto pilot
> > servos & control boxs be grounded locally or should they be run up to the
> > common ground point?
> > I have a rear mounted battery on my RV-8A project. The pitch servo &
> > controller are only 6 - 8" from my battery. Should I ground them directly
> > to the battery?
>
> What do the instructions say? Posting a question
> like that on the List is fraught with risk. You need
> to do it only when the instructions are not clear -AND-
> attempts to clarify ambiguous instructions with
> the manufacturer has failed or is impossible.
>
> Then your ONLY recourse is to seek learned advice.
> However, unless the responding individuals have first hand
> knowledge unique to the product, then the best you
> can hope for is an educated guess.
>
> I'll suggest it's FAR better to exhaust all opportunities
> for the "good" advice before you resort to "best guess"
> advice.
>
> Bob . . .
>
>
>
>
>
>
Message 8
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| Subject: | Re: OVP, Alternators, and stuff |
--> AeroElectric-List message posted by: Mickey Coggins <mick-matronics@rv8.ch>
>>>However, the Kilovac Czonka III P/N
>>>EV200AAANA will do the job easily--200A Interrupt at 320V. As a bonus its
>>>coil draws only 100 milliamps.
>
>
>>Eric, are you saying this is the relay you recommend in this
>>diagram: http://www.periheliondesign.com/OVP/OVschems.gif
> That's affirmative. I have a load of these for sale at $80 each (I
> think...email me offlist). Nothing else I know is sure to do the job. My
Will do.
> approach is to eliminate all the other contactors anyway so this one is the
> only one you need. When you consider it, the race car battery switches are
> better than battery contactor; ...
Sounds interesting. Do you have one you recommend, and will they
work for rear mounted batteries? I've already got mine hooked up
with standard contactors, but it's always fun to learn something
new.
--
Mickey Coggins
http://www.rv8.ch/
#82007 finishing
do not archive
Message 9
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| Subject: | Re: Auto Pilot Servo Ground wire |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 12:46 PM 7/15/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: <chaztuna@adelphia.net>
>
>
>---- "Robert L. Nuckolls wrote:
> > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <nuckollsr@cox.net>
> >
> > At 02:16 PM 7/14/2005 -0400, you wrote:
> >
> > P.S. if you get a good answer from Trutrak, please
> > share it with us on the list so that it gets stashed
> > in the archives. Let us know who you talked, their
> > phone number and what was advised along with any
> > explanations they may have to offer.
> >
> > Bob . . .
>
>Bob,
> I spoke to tech support at Trutrak this morning. They told me to make
> all the grounds at a single point.
>Charlie Kuss
Good data. Thanks. I might have guessed that but
now we can ALL speak to the question with a higher
degree of certainty. As a rule-of-thumb, one is almost
never wrong grounding all components of a single system
at the same place. When that system shares data or control
lines with a second system, then it's good that both of those
systems ground at the same place too.
In terms of your original question I'll suggest it
doesn't matter in terms of system performance whether
you ground all stuff at the battery or at the firewall
ground bus . . . they're best grounded TOGETHER.
Bob . . .
Message 10
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| Subject: | Re: A question on my crossbar overvoltage |
protection
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
Hi Bob
It's obvious that you are a busy man and I thank you for your
observations. No this is not a 40amp breaker. It's a small automotive
relay with 40 amp rated contacts. It provides an OV disconnect for a 20
amp PM alternator. The relay coil draws about 130 ma. The circuit
breaker that feeds this relay coil, and that the Crowbar OVP trips, is
a 2 1/2 amp (two and a half amp) breaker.
The OVP is not from B&C. It is homemade according to the revision dated
4/16/2 and constructed with the recommended Digi-key parts. Since you
have confirmed that this is unexpected behaviour, I will do some more
investigation and let you know what I find.
This is on a modified Z-14 and it is not even on the battery that feeds
the primary systems of my electrically dependant engine. This battery
and PM alternator feeds the backup engine systems. I'll start by
investigating whether the OVP for the other alternator behaves similarly
and perhaps put a scope on the 22 uF capacitor and the SCR. If I don't
learn anything useful and it is still exhibiting this behaviour, I'll be
happy to donate it to the cause if you still want to see it but it is
just a homemade unit.
thanks
Ken
Robert L. Nuckolls, III overvoltage protection wrote:
>--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
overvoltage protection
>
>At 05:50 PM 7/14/2005 -0400, you wrote:
>
>
>
>>--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
>>
>>I wonder if this is related to what I reported a month or so ago?
>>
>>"While tracking down a electrical problem ( haven't run the engine yet)
>>I was sidetracked for awhile by the circuit breaker that feeds a 40 amp
>>OV relay on my permanent magnet alternator popping.
>>
>>
>
> ???? 40A breaker ???? What power distribution diagram are
> you using?
>
>
>> It seems that
>>wiggling a loose connection between the breaker and the relay will trip
>>the OVP and open the breaker. The crowbar OVP is constructed from the
>>new design. It tests OK and it doesn't trip if the alternator switch is
>>operated. It does trip if I intentionally rapidly connect and disconnect
>>the wire to the relay. The relay coil draws about 130 mA. If I
>>disconnect the OVP I am unable to make the C/B trip so it would seem
>>that the OVP is activating. It doesn't seem to make any difference
>>whether a diode is across the relay coil.
>>
>>
>
> Hmmm . . .
>
>
>
>>I'm guessing this is normal and I'm making voltage spikes at a faster
>>rate than the OVP time delay resets but I would have expected negative
>>spikes rather than positive spikes. "
>>
>>
>
> It might be "normal" but not expected. I can deduce no
> feature of the design that would "pump up" the ov protection
> to some trip level based on the intermittent connection
> you describe.
>
>
>
>
>>At that time I also said that "temporarilly adding a unidirectional
>>transorb across it makes it more resistant to tripping which seems to
>>confirm that I am generating positive spikes" but in retrospect I'm not
>>certain that the transorb made much difference. Since I can't cycle the
>>switch fast enough to cause a problem and nobody commented, I tightened
>>my loose connection and did not persue this further.
>>
>>
>
> Interesting. I'm sorry I missed the original discussion. I presume
> your talking about an OVM-14 from B&C. I've not had any activity
> with that product for several years. I'd like to get yours back
> to see if I can duplicate your experience on the bench. Shoot
> me your address and I'll send you a new one and a return envelope
> for the old one.
>
> I'll remind everyone that I'm intently interested in pursuing
> this kind of investigation on products of any manufacture and
> if I don't pick up on the conversation from a routine List
> posting, send me a direct e-mail through the website at:
>
> http://www.aeroelectric.com/bob.nuckolls/ (I'm use this to
> avoid posting the "real" address for 'bots' to find.)
>
> I've got a lot of balls in the air at once and I don't
> want folks to believe my inattention is an overt avoidance of
> the issue.
>
> Bob. . .
>
>
Message 11
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| Subject: | Re: OVP, Alternators, and stuff |
--> AeroElectric-List message posted by: plaurence@the-beach.net
On 15 Jul 2005 at 10:34, Eric M. Jones wrote:
> --> AeroElectric-List message posted by: "Eric M. Jones"
> <emjones@charter.net>
>
> --> AeroElectric-List message posted by: Mickey Coggins
> <mick-matronics@rv8.ch>
>
>> one is the only one you need. When you consider it, the race car
> battery switches are better than battery contactor; the starter
> contactor is only used to allow the use of a wimpy ignition keyswitch;
> the ground power contactor is unnecessary, and the crossfeed contactor
> can easily be eliminated (but I have too much yardwork to do to
> describe the details....).
>
Eric
What manly keyswitch would use for the starter? Also, I believe the contactor is
used so that in case the
solenoid sticks and the ring gear remains engaged, there is no power to the starter.
Peter
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