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Over-voltage event w/ IR alternator

 
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bob(at)flyboybob.com
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PostPosted: Mon Feb 13, 2006 3:35 am    Post subject: Over-voltage event w/ IR alternator Reply with quote

Yesterday morning on the way to church I noticed the alternator idiot light
come on. A quick check of the volt meter indicated 18 volts. I was driving
my son's 1990 Ford F-150 with an IR alternator. It took me about thirty
seconds to figure out what to do. There was not enough time left before
church to make a forced landing so I kept flying. I started turning on
anything electrical to absorb the extra electrons that were smashing the
battery. When I remembered the off road driving lights my son recently
installed and turned them on I was down to 13 volts. The voltage would
varry with RPM and as long as I kept everything on and the RPM below 1500 I
could keep the voltage under 14 volts. As the truck accelerated away from a
stop and the transmission was in lower gears the idiot light would come on
each time the voltage was above 16 volts which happened around 2000 RPM.
Once in high gear the RPM would settle around 1200 and the voltage would be
around 13 volts.

In thirty years of driving I would guess that I have had five or six
alternator failures. This is the first time it has been a high voltage
failure. All of the other times it has been low output failures.

Conclusions:
1. some IR alternators out there will detect an overvoltage event (turn
on the idiot light) and yet do nothing about it (continue to produce 18
volts).
2. one event does not make conclusive scinece
3. a check list for OV events would have solved this problem quicker - I
need a plan for low frequency failures with simple solutions.
4. z-13 would have handled this problem in my airplane as the main
alternator would have tripped the OV module; the low voltage tone in my
earphones would alert me to turn on the standby alternator and flight would
have continued to destination.
5. what I learned from conclusions 1, 3, and 4 is worth the risk of
starting another IR alternator e-mail flood.
6. I'm glad I removed the IR regulator from my plane's alternator and
replaced it with an external unit and OV module.

Just remember, everything I say could be wrong - or right?

Regards,

Bob Lee
KR2 N52BL
91% done only 63% to go!


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rv8ch



Joined: 10 Jan 2006
Posts: 250
Location: Switzerland

PostPosted: Mon Feb 13, 2006 4:21 am    Post subject: Over-voltage event w/ IR alternator Reply with quote

> Yesterday morning on the way to church I noticed the alternator idiot
light
Quote:
come on. A quick check of the volt meter indicated 18 volts. ...

Was that the standard voltmeter that is installed in the car?

What is the scale of the gauge?

What brand of IR alternator are we talking about?

Quote:
5. what I learned from conclusions 1, 3, and 4 is worth the risk of
starting another IR alternator e-mail flood.

I'm not sure I agree with you! Smile

Thanks,
Mickey

--
Mickey Coggins
http://www.rv8.ch/
#82007 finishing
do not archive


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Mickey Coggins
http://www.rv8.ch/
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nuckollsr(at)cox.net
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PostPosted: Mon Feb 13, 2006 5:06 am    Post subject: Over-voltage event w/ IR alternator Reply with quote

At 06:34 AM 2/13/2006 -0500, you wrote:

Quote:


Yesterday morning on the way to church I noticed the alternator idiot light
come on. A quick check of the volt meter indicated 18 volts. I was driving
my son's 1990 Ford F-150 with an IR alternator. It took me about thirty
seconds to figure out what to do. There was not enough time left before
church to make a forced landing so I kept flying. I started turning on
anything electrical to absorb the extra electrons that were smashing the
battery. When I remembered the off road driving lights my son recently
installed and turned them on I was down to 13 volts. The voltage would
varry with RPM and as long as I kept everything on and the RPM below 1500 I
could keep the voltage under 14 volts. As the truck accelerated away from a
stop and the transmission was in lower gears the idiot light would come on
each time the voltage was above 16 volts which happened around 2000 RPM.
Once in high gear the RPM would settle around 1200 and the voltage would be
around 13 volts.

In thirty years of driving I would guess that I have had five or six
alternator failures. This is the first time it has been a high voltage
failure. All of the other times it has been low output failures.

Conclusions:
1. some IR alternators out there will detect an overvoltage event (turn
on the idiot light) and yet do nothing about it (continue to produce 18
volts).
2. one event does not make conclusive scinece
3. a check list for OV events would have solved this problem quicker - I
need a plan for low frequency failures with simple solutions.
4. z-13 would have handled this problem in my airplane as the main
alternator would have tripped the OV module; the low voltage tone in my
earphones would alert me to turn on the standby alternator and flight would
have continued to destination.
5. what I learned from conclusions 1, 3, and 4 is worth the risk of
starting another IR alternator e-mail flood.
6. I'm glad I removed the IR regulator from my plane's alternator and
replaced it with an external unit and OV module.

Just remember, everything I say could be wrong - or right?


The things you've offered are reasonable deductions based on
irrefutable observation and an understanding of the simple ideas
upon which the failed system functions. Using these tools, the
probability of having good ideas to offer is quite high. I can
find no faults in your narration.

The most profound observation I would offer is that because of
your willingness to learn, understand, observe, react and
craft a Plan-B on the fly (load it up and keep rpm low) is
gratifying to me. As engineer I KNOW that ALL alternator/regulator
combinations have operating/failure modes wherein there is benefit
for crafting the automatic (or at least a rapid-response manual)
control philosophy.

The difficult task is as teacher to share that knowledge in ways
that impart understanding. If what you've shared with us today
is based at least in part on understanding you've acquired here
on the List, then you've made my day sir. Know that there are
ways to add positive, low stress control to an IR alternator and the
hardware for doing that will be available in due course. Thank
you for sharing your contribution with us.

I'm off to class today. RAC offered me a short course (35 hours)
from KU on flight testing. I'm sure that most of the course
materials have to do with the investigation of an airplane's
aerodynamics and structural integrity which is way out of my
field of expertise. But the most successful test programs
are those which are well instrumented and supported by tools for
evaluating data. You ought to see how Eclipse has conducted
their flight tests! I'm looking forward to a week of immersion
in, as #5 would say, "input". This is going to be a good week.

Bob . . .


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bob(at)flyboybob.com
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PostPosted: Mon Feb 13, 2006 5:36 am    Post subject: Over-voltage event w/ IR alternator Reply with quote

Mickey asked: [answers in [] brackets]

Was that the standard voltmeter that is installed in the car? [Ford Factory]

What is the scale of the gauge? [8 to 18 volts in 1 volt incriments]

What brand of IR alternator are we talking about? [Stock Ford]

Quote:
5. what I learned from conclusions 1, 3, and 4 is worth the risk of
starting another IR alternator e-mail flood.

I'm not sure I agree with you! Smile [like I said, everything I said could
be wrong!]

Regards,

Bob Lee
KR2 N52BL
91% done only 63% to go!


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gmcjetpilot(at)yahoo.com
Guest





PostPosted: Tue Feb 14, 2006 11:43 am    Post subject: Over-voltage event w/ IR alternator Reply with quote

Mr. Bob Lee

Congratulation you had an overvoltage. You saw
that it limited the voltage to 18 volts max. I
think your volt meter is off and it was likely more
like 17 volts, but that is what the ND alternators
do. Their secondary voltage control limit is either
16v or 17v on some models. Not sure about a
Ford alternator, but all I-VR alternators (really the
only ones made now a day) use similar IC chip
control in the VR and OV limit of 17v max.

Even though you had an overvoltage you had some
control and never exceeded 18 volts (17 volts?).

Thanks for an excellent factual description with
out sensational emotional and prejudicial
comments. Yes an I-VR can have an OV but not the
wild runaway that gets spread around like brown
stinky stuff. Although OV is rare in the first place,
this is typical overvoltage when it does happen.

Bob and some dislike the I-VR because there is one
transistor that controls the field. If that transistor
failed (single point failure) it could in THEORY cause
a high uncontrolled OV condition. NO one has proved
this has EVER happened as they say. By prove I
mean took a claimed runaway VR and determined the
cause was this single point failure. Its RARE indeed.

In practice the field transistor is bullet proof.

Cooling air adds to the reliability of that or any transistor.

Don't install a I-VR like a E-VR they are differnt by design.

That is my only point I have tried to make in a
year of fighting the anecdotal comments Bob and
other's make. NO OFFENSE TO BOB. I agree the
E-VR has MORE control or should say more DIRECT
control of the fundamental thing that controls
output, the field wire. THAT IS AN ADVANTAGE.

(SEE I SAID IT, BUT THAT does not make I-VR bad.)

However let's be real. I-VR are super reliable as
is. Failures are rare and tend to be LOW voltage
or NO voltage events. When there is a spike above
the normal set voltage its a controllable event
by adding load.

Example in point: F150 Ford truck, IF YOU HAVE a
pull-able CB in your FORD truck for the alternator
output (b-lead), you would just pull the CB if the
voltage was too high. Done deal. No need for extra
protection or crow bars.

HOWEVER I KNOW BOB'S philosophy that he likes
automatic control. OK that is cool. However that
comes at the expense of weight, complexity and
potential nuisance trips that can damage a good
alternator.

BOB contradicts himself, saying don't use an I-VR at all?

OK great advice, but a problem?

NO ONE makes cheap off the shelf E-VR alternators?

Why spend++$600 for B&C or GUT a perfectly good I-VR?

Bottom line, Lee's alternator not only indicated
the OV failure, which shows the value of using the
warning light, the voltage never exceeded 18v (I
think you volt gauge is off by a volt). WHAT IS
WRONG WITH THAT? Most avionics can take anywhere
from 10-30 volts all day with out fail and even a
spike up to 60v for very short durations.

HERE HERE Mr. Lee!!!!!

Well done. I am putting you in my email post HALL
OF FAME. I agree with all you points except point
6, your conclusion, but than its not that point 6
is incorrect. I can't fault anything you said. I
just don't think its necessarily a needed.

Of your 6 points I summit the following comments:

1) The alternator defaults to 18v (17v?) by
design and typical. It is also NOT
indicative of the claim that the field has
gone crazy. There is a fault and it has lost
some control, but it is NOT out of control.

2) One event does not make a case, but your
experience is typical. In the rare cases of
OV (anything over 14.5v).


3) Check list are great


4) Z-13 would but so would reach over and
pulling a CB on the B-lead. I am not sure
turning the IGN "signal" to tell the VR to
go to sleep will work every time. Bob says
he does not recommend I-VR at all any more
any way, so if you are a disciple of his
doctrine the solution is obvious. I have no
issue with that.


5) I think it is worth the risk of good debate.


6) I am glad for you all the best. What ever
makes you sleep at night. By the way Ford
alternators have a bad service history
according to the NHTSA (Nits-a) (National
Highway Traffic Safety Administration). ND
alternators are as prolific and have a
spotless record in regards to consumer
complain, service bulletins and recalls.


My points are:


a) use the warning light; it is a fault light
not just a no charge light. If you don't use
the warning light, have something to
indicate a charge fault (hi/lo volts).


b) Do not turn the alternator on and off under
load.


c) Wire it (the ND alternator Van sells) just
like I show below. Which is a copy of how it
works in the Suzuki Samurai it was designed
for with one addition for aircraft use, the
50-60 amp pull-able CB in the panel.

d) If you want an I-VR and an OV relay and crow
bar, that is fine but you would be better
off going to an external VR if you can't
live with the I-VR as is, which is Bob Lee's
conclusion. I can't fault you for that. DO
what makes you happy.


http://img116.imageshack.us/my.php?image=altwiring5cm.jpg

A modified Toyota diagram.

http://img110.imageshack.us/my.php?image=toyota7gf.jpg



Flame Suit on. BTW please actually read what I
wrote first. I said external VR's are better in
that you have direct access to the field wire. I
also said I agree with Bob N and Bob L and
understand the desire to either use an OV
module/relay on an I-VR or use an E-VR.

I AGREE. Back off.

The only point I need to make is OV events with I-
VR's are rare, which Bob Lee made for me. I also need
to point out the SO CALLED overvoltage event was a
NON EVENT. In a car or plane it does little to
nothing since most devices can live on 17volts (or
even 18 volts as Bob Lee said, which I think is a
little high). AT LEAST this event was well
document and valid case to evaluate and its impact
on aircraft operations. Obviously Mr. Lee in his
F150 could just pull over and CRASH LAND on the
shoulder of the road. In a plane pulling over and
parking on a cloud is not possible. However that
is what a battery is for.

Sincerely George Nomex flame suit on.



From: <bob(at)flyboybob.com>
Subject: Over-voltage event w/ IR alternator
Message posted by: <bob(at)flyboybob.com>

Yesterday morning on the way to church I noticed
the alternator idiot Light come on. A quick check
of the volt meter indicated 18 volts. I was
Driving my son's 1990 Ford F-150 with an IR
alternator. It took me about Thirty seconds to
figure out what to do. There was not enough time
left Before church to make a forced landing so I
kept flying. I started turning on anything
electrical to absorb the extra electrons that were
smashing the battery. When I remembered the off
road driving lights my son recently installed and
turned them on I was down to 13 volts. The
voltage would vary with RPM and as long as I kept
everything on and the RPM below 1500 I could keep
the voltage under 14 volts. As the truck
accelerated away from a stop and the transmission
was in lower gears the idiot light would come on
each time the voltage was above 16 volts which
happened around 2000 RPM. Once in high gear the
RPM would settle around 1200 and the voltage would
be around 13 volts.

In thirty years of driving I would guess that I
have had five or six alternator failures. This is
the first time it has been a high voltage failure.
All of the other times it has been low output
failures.

Conclusions:


1. some IR alternators out there will detect an
overvoltage event (turn on the idiot light) and
yet do nothing about it (continue to produce 18
volts).

2. one event does not make conclusive science

3. a check list for OV events would have solved
this problem quicker. I need a plan for low
frequency failures with simple solutions.

4. z-13 would have handled this problem in my
airplane as the main alternator would have tripped
the OV module; the low voltage tone in my
earphones would alert me to turn on the standby
alternator and flight would have continued to
destination.

5. what I learned from conclusions 1, 3, and 4
is worth the risk of starting another IR
alternator e-mail flood.

6. I'm glad I removed the IR regulator from my
plane's alternator And replaced it with an
external unit and OV module.

Just remember, everything I say could be wrong - or right?
Regards,
Bob Lee
KR2 N52BL
91% done only 63% to go!


---------------------------------
Brings words and photos together (easily) with


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mprather(at)spro.net
Guest





PostPosted: Tue Feb 14, 2006 1:25 pm    Post subject: Over-voltage event w/ IR alternator Reply with quote

Hello George,

A couple of questions:

What causes the failed IR overvoltage event to max-out at 17V (or 18V)?
Is it loads and battery? Or is the field current limited somehow. It
seems that we discussed that a short between Vb and the field (through the
main transistor, or otherwise) would cause cause an OV event similar to
what was described - open loop output, controlled by RPM, and load - the
battery being the primary load. Mr Lee didn't mention whether he
experimented with eliminating loads, and revving the engine to a higher
RPM (I wouldn't have tried that on my daily driver). But it seems that
you are suggesting that even had he done that, 17V would have been the
peak voltage seen on the bus. Am I reading you right?

How long can we predict that we can leave a typical 17Ah AGM battery
connected to 17V, and have it act as a system filter? Is there any risk
of fire associated with long term (admittedly, unquantified) operation in
such a manner? Asked another way, what's the charge rate on the battery
when pumped to 17V? I suppose your suggestion to include a b-lead
disconnect of some sort (breaker, in your case) addresses this issue. As
long as the pilot registers that the bus voltage is significantly out of
limits.

Without intending to put words into Bob (Nuckolls)'s mouth, I believe he
has said that he can't recommend IR alternators in the context of
designing an electrical system with certificated-like behavior. Not an
all-out condemnation of these alternators as a whole. I believe he has,
on several occasions, recognized the advantages of these low-cost devices.
Regards,

Matt-
Quote:


Mr. Bob Lee

Congratulation you had an overvoltage. You saw
that it limited the voltage to 18 volts max. I
think your volt meter is off and it was likely more
like 17 volts, but that is what the ND alternators
do. Their secondary voltage control limit is either
16v or 17v on some models. Not sure about a
Ford alternator, but all I-VR alternators (really the
only ones made now a day) use similar IC chip
control in the VR and OV limit of 17v max.

Even though you had an overvoltage you had some
control and never exceeded 18 volts (17 volts?).

Thanks for an excellent factual description with
out sensational emotional and prejudicial
comments. Yes an I-VR can have an OV but not the
wild runaway that gets spread around like brown
stinky stuff. Although OV is rare in the first place,
this is typical overvoltage when it does happen.

Bob and some dislike the I-VR because there is one
transistor that controls the field. If that transistor
failed (single point failure) it could in THEORY cause
a high uncontrolled OV condition. NO one has proved
this has EVER happened as they say. By prove I
mean took a claimed runaway VR and determined the
cause was this single point failure. Its RARE indeed.

In practice the field transistor is bullet proof.

Cooling air adds to the reliability of that or any transistor.

Don't install a I-VR like a E-VR they are differnt by design.

That is my only point I have tried to make in a
year of fighting the anecdotal comments Bob and
other's make. NO OFFENSE TO BOB. I agree the
E-VR has MORE control or should say more DIRECT
control of the fundamental thing that controls
output, the field wire. THAT IS AN ADVANTAGE.

(SEE I SAID IT, BUT THAT does not make I-VR bad.)

However let's be real. I-VR are super reliable as
is. Failures are rare and tend to be LOW voltage
or NO voltage events. When there is a spike above
the normal set voltage its a controllable event
by adding load.

Example in point: F150 Ford truck, IF YOU HAVE a
pull-able CB in your FORD truck for the alternator
output (b-lead), you would just pull the CB if the
voltage was too high. Done deal. No need for extra
protection or crow bars.

HOWEVER I KNOW BOB'S philosophy that he likes
automatic control. OK that is cool. However that
comes at the expense of weight, complexity and
potential nuisance trips that can damage a good
alternator.

BOB contradicts himself, saying don't use an I-VR at all?

OK great advice, but a problem?

NO ONE makes cheap off the shelf E-VR alternators?

Why spend++$600 for B&C or GUT a perfectly good I-VR?

Bottom line, Lee's alternator not only indicated
the OV failure, which shows the value of using the
warning light, the voltage never exceeded 18v (I
think you volt gauge is off by a volt). WHAT IS
WRONG WITH THAT? Most avionics can take anywhere
from 10-30 volts all day with out fail and even a
spike up to 60v for very short durations.

HERE HERE Mr. Lee!!!!!

Well done. I am putting you in my email post HALL
OF FAME. I agree with all you points except point
6, your conclusion, but than its not that point 6
is incorrect. I can't fault anything you said. I
just don't think its necessarily a needed.

Of your 6 points I summit the following comments:

1) The alternator defaults to 18v (17v?) by
design and typical. It is also NOT
indicative of the claim that the field has
gone crazy. There is a fault and it has lost
some control, but it is NOT out of control.

2) One event does not make a case, but your
experience is typical. In the rare cases of
OV (anything over 14.5v).
3) Check list are great
4) Z-13 would but so would reach over and
pulling a CB on the B-lead. I am not sure
turning the IGN "signal" to tell the VR to
go to sleep will work every time. Bob says
he does not recommend I-VR at all any more
any way, so if you are a disciple of his
doctrine the solution is obvious. I have no
issue with that.
5) I think it is worth the risk of good debate.
6) I am glad for you all the best. What ever
makes you sleep at night. By the way Ford
alternators have a bad service history
according to the NHTSA (Nits-a) (National
Highway Traffic Safety Administration). ND
alternators are as prolific and have a
spotless record in regards to consumer
complain, service bulletins and recalls.
My points are:
a) use the warning light; it is a fault light
not just a no charge light. If you don't use
the warning light, have something to
indicate a charge fault (hi/lo volts).
b) Do not turn the alternator on and off under
load.
c) Wire it (the ND alternator Van sells) just
like I show below. Which is a copy of how it
works in the Suzuki Samurai it was designed
for with one addition for aircraft use, the
50-60 amp pull-able CB in the panel.

d) If you want an I-VR and an OV relay and crow
bar, that is fine but you would be better
off going to an external VR if you can't
live with the I-VR as is, which is Bob Lee's
conclusion. I can't fault you for that. DO
what makes you happy.
http://img116.imageshack.us/my.php?image=altwiring5cm.jpg

A modified Toyota diagram.

http://img110.imageshack.us/my.php?image=toyota7gf.jpg

Flame Suit on. BTW please actually read what I
wrote first. I said external VR's are better in
that you have direct access to the field wire. I
also said I agree with Bob N and Bob L and
understand the desire to either use an OV
module/relay on an I-VR or use an E-VR.

I AGREE. Back off.

The only point I need to make is OV events with I-
VR's are rare, which Bob Lee made for me. I also need
to point out the SO CALLED overvoltage event was a
NON EVENT. In a car or plane it does little to
nothing since most devices can live on 17volts (or
even 18 volts as Bob Lee said, which I think is a
little high). AT LEAST this event was well
document and valid case to evaluate and its impact
on aircraft operations. Obviously Mr. Lee in his
F150 could just pull over and CRASH LAND on the
shoulder of the road. In a plane pulling over and
parking on a cloud is not possible. However that
is what a battery is for.

Sincerely George Nomex flame suit on.

From: <bob(at)flyboybob.com>
Subject: Over-voltage event w/ IR alternator
Message posted by: <bob(at)flyboybob.com>

Yesterday morning on the way to church I noticed
the alternator idiot Light come on. A quick check
of the volt meter indicated 18 volts. I was
Driving my son's 1990 Ford F-150 with an IR
alternator. It took me about Thirty seconds to
figure out what to do. There was not enough time
left Before church to make a forced landing so I
kept flying. I started turning on anything
electrical to absorb the extra electrons that were
smashing the battery. When I remembered the off
road driving lights my son recently installed and
turned them on I was down to 13 volts. The
voltage would vary with RPM and as long as I kept
everything on and the RPM below 1500 I could keep
the voltage under 14 volts. As the truck
accelerated away from a stop and the transmission
was in lower gears the idiot light would come on
each time the voltage was above 16 volts which
happened around 2000 RPM. Once in high gear the
RPM would settle around 1200 and the voltage would
be around 13 volts.

In thirty years of driving I would guess that I
have had five or six alternator failures. This is
the first time it has been a high voltage failure.
All of the other times it has been low output
failures.

Conclusions:
1. some IR alternators out there will detect an
overvoltage event (turn on the idiot light) and
yet do nothing about it (continue to produce 18
volts).

2. one event does not make conclusive science

3. a check list for OV events would have solved
this problem quicker. I need a plan for low
frequency failures with simple solutions.

4. z-13 would have handled this problem in my
airplane as the main alternator would have tripped
the OV module; the low voltage tone in my
earphones would alert me to turn on the standby
alternator and flight would have continued to
destination.

5. what I learned from conclusions 1, 3, and 4
is worth the risk of starting another IR
alternator e-mail flood.

6. I'm glad I removed the IR regulator from my
plane's alternator And replaced it with an
external unit and OV module.

Just remember, everything I say could be wrong - or right?
Regards,
Bob Lee
KR2 N52BL
91% done only 63% to go!
---------------------------------
Brings words and photos together (easily) with



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Back to top
brian



Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

PostPosted: Tue Feb 14, 2006 3:18 pm    Post subject: Over-voltage event w/ IR alternator Reply with quote

gmcjetpilot(at)yahoo.com wrote:
Quote:
Bob and some dislike the I-VR because there is one
transistor that controls the field. If that transistor
failed (single point failure) it could in THEORY cause
a high uncontrolled OV condition. NO one has proved
this has EVER happened as they say. By prove I
mean took a claimed runaway VR and determined the
cause was this single point failure. Its RARE indeed.

Failure of the pass transistor in internally regulated or externally
regulated alternators and generators is rare but it does happen. Bob is
working on an OV protection circuit for the Nanchang CJ6A for just this
reason. The pass transistor in the VR shorts and turns the generator on
hard. (Late-model transistorized regulator, not the old
electromechanical regulator.) In one case it caused the battery to catch
fire. In another case the battery exploded causing substantial damage to
the aircraft. This is a dangerous failure that can result in the
destruction of the aircraft in flight if it happens. It deserves attention.

Quote:
In practice the field transistor is bullet proof.

Uh, no, that is not quite true. It is a transistor. It can fail. And
when it fails, it can fail shorted leading to an OV situation.

Quote:
1) The alternator defaults to 18v (17v?) by
design and typical. It is also NOT
indicative of the claim that the field has
gone crazy.

Crazy? Not a lot of useful information in that description. If you mean
that the pass transistor has shorted and turned the field on hard
leading to runaway high-voltage output, then, yes, that is the problem.

Quote:
There is a fault and it has lost
some control, but it is NOT out of control.

I happen to think you are wrong but humor me. This is easy enough to
figure out if you can get to the field winding. Throw a 'scope
(something we idiot technicians know how to use) on the field and look
for the field being turned on and off rapidly (PWM control). If it is
always on, the pass transistor in the VR is failed shorted.

Quote:
2) One event does not make a case, but your
experience is typical. In the rare cases of
OV (anything over 14.5v).

If it happens once, it will happen again. They can fail and when they
do, they will do serious damage to the battery and possibly the avionics.

Transistors do fail. That they are inside or outside the body of the
alternator does not change this fact.

Brian Lloyd
brian-yak(at)lloyd.com


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PostPosted: Tue Feb 14, 2006 4:44 pm    Post subject: Over-voltage event w/ IR alternator Reply with quote

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

gmcjetpilot(at)yahoo.com wrote:

Quote:
Congratulation you had an overvoltage. You saw
that it limited the voltage to 18 volts max. I

Since the range of the voltmeter in question only extended to 18 volts,
it doesn't seem that we can confidently say what the voltage was, only
that it was at least 18 volts (or at least whatever voltage causes the
instrument to register 18 volts). The accuracy of the gauge could be
determined easily enough by cross-checking using a DVM of known
accuracy, so long as it was connected to the same place that the panel
meter uses--but that's really a side issue. As the scenario was
described, the voltmeter was pegged at 18 volts--you can't say from that
that the resulting voltage was 18 max; it's more like 18 min.

- --
Dan Brown, KE6MKS, dan(at)familybrown.org
"Since all the world is but a story, it were well for thee to buy the
more enduring story rather than the story that is less enduring."
-- The Judgment of St. Colum Cille
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PostPosted: Tue Feb 14, 2006 4:59 pm    Post subject: Over-voltage event w/ IR alternator Reply with quote

At 02:20 PM 2/14/2006 -0700, you wrote:

Quote:


Hello George,

A couple of questions:

What causes the failed IR overvoltage event to max-out at 17V (or 18V)?
Is it loads and battery?

Yes, recall the power system dynamics article I started last
spring:

http://www.aeroelectric.com/articles/Crowbar_OV_Protection/DC_Power_System_Dynamics_C.pdf

Starting on page 6 we explore the battery's ability to stand
of the output of a runaway alternator . . .
Quote:
Or is the field current limited somehow. It
seems that we discussed that a short between Vb and the field (through the
main transistor, or otherwise) would cause cause an OV event similar to
what was described - open loop output, controlled by RPM, and load - the
battery being the primary load. Mr Lee didn't mention whether he
experimented with eliminating loads, and revving the engine to a higher
RPM (I wouldn't have tried that on my daily driver). But it seems that
you are suggesting that even had he done that, 17V would have been the
peak voltage seen on the bus. Am I reading you right?

How long can we predict that we can leave a typical 17Ah AGM battery
connected to 17V, and have it act as a system filter?

Depends on the size of the battery, its construction and it's
station in service life. The newer the battery, and assuming it's
an RG battery, it will hold a 60A alternator to something under
20 volts for some period of time. I'd guess maybe a minute or
more.
Quote:
Is there any risk
of fire associated with long term (admittedly, unquantified) operation in
such a manner?

Yes but slight. Remember this Odyssey battery we got from a Lister
who had suffered an ov condition? See pictures at:

http://www.aeroelectric.com/Pictures/Battery/Odyssey_OV/Odyssey_OV_1.jpg

But the risk is non-existent if you have some form of
ov warning, if only a light. You have some period of
time from onset of ov condition until things start coming
unglued.
Quote:
Asked another way, what's the charge rate on the battery
when pumped to 17V? I suppose your suggestion to include a b-lead
disconnect of some sort (breaker, in your case) addresses this issue. As
long as the pilot registers that the bus voltage is significantly out of
limits.

Without intending to put words into Bob (Nuckolls)'s mouth, I believe he
has said that he can't recommend IR alternators in the context of
designing an electrical system with certificated-like behavior. Not an
all-out condemnation of these alternators as a whole. I believe he has,
on several occasions, recognized the advantages of these low-cost devices.

Back in December, I posted this response:
Quote:
Bob,

Any recent updates on the "internally regulated alternator"?

I know that you were not recommending it's use on an "all electric
airplane with dual electronic ignition", which is the configuration of the
plane I am building.

Not at all. The modern internally regulated alternator
is a great piece of hardware that offers excellent value
over most 60's certified alternators flying today. Your
choice of alternators has nothing to do with whether or
not you have electronic ignition, EFIS, or any other
modern feature.

Depending on WHICH IR alternator you choose, you may not
have 100%, absolute control over it's output which
does not satisfy traditional design goals.

Further, depending on WHICH IR alternator you choose,
you may not be able to add a convenient form of
OV protection which is also a traditional design
goal.

Finally, depending on WHICH IR alternator you choose,
the act of turning it on and OFF at inopportune times
may damage the alternator's regulator.

Having offered this, there are thousands of OBAM
aircraft flying wherein the builder has not included
these points in satisfaction of his own design goals
either because he has considered them insignificant
or doesn't understand them well enough to make a
well considered decision. None-the-less, a vast
majority of these aircraft ARE flying trouble free.

However, from time to time, we're made aware of
installations where the builder wishes he had
considered and adopted the traditional design
goals. It's a small percentage to be sure . . .
but then catastrophic runaway failures in the
certified ships also constitutes a small percentage
of all failures.

Bottom line is that we will be able to offer a means
by which any internally regulated alternator can
be integrated into your airplane under the traditional
design goals. In the mean time, drive on with whatever
installation instructions come with your alternator
of choice knowing that modifying the system will be
easy and inexpensive at a later time. I've been trying
to get the next few pages of "Understanding Alternators"

http://www.aeroelectric.com/articles/alternators/UA/Alternators_1.html
published but things are really busy around here this
time of year.
---------------------------------------

I've been working on the "Understanding Alternators" article
and plan to combine it with the DC Power System Dynamics
article.
Bob . . .


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PostPosted: Tue Feb 14, 2006 5:30 pm    Post subject: Over-voltage event w/ IR alternator Reply with quote

Exactly what I was thinking Dan.
Even though the idiot light came on, without further info or testing of
the alternator I see no reason to assume that there was secondary OV
protection operating in this example. Maybe it was, maybe it wasn't.
Ken

Dan Brown wrote:

Quote:


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

gmcjetpilot(at)yahoo.com wrote:



>Congratulation you had an overvoltage. You saw
>that it limited the voltage to 18 volts max. I
>
>

Since the range of the voltmeter in question only extended to 18 volts,
it doesn't seem that we can confidently say what the voltage was, only
that it was at least 18 volts (or at least whatever voltage causes the
instrument to register 18 volts). The accuracy of the gauge could be
determined easily enough by cross-checking using a DVM of known
accuracy, so long as it was connected to the same place that the panel
meter uses--but that's really a side issue. As the scenario was
described, the voltmeter was pegged at 18 volts--you can't say from that
that the resulting voltage was 18 max; it's more like 18 min.

- --
Dan Brown, KE6MKS, dan(at)familybrown.org




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PostPosted: Wed Feb 15, 2006 5:18 am    Post subject: Over-voltage event w/ IR alternator Reply with quote

At 07:47 PM 2/14/2006 -0500, you wrote:

Quote:


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

gmcjetpilot(at)yahoo.com wrote:

> Congratulation you had an overvoltage. You saw
> that it limited the voltage to 18 volts max. I

Since the range of the voltmeter in question only extended to 18
volts,
it doesn't seem that we can confidently say what the voltage was, only
that it was at least 18 volts (or at least whatever voltage causes the
instrument to register 18 volts). The accuracy of the gauge could be
determined easily enough by cross-checking using a DVM of known
accuracy, so long as it was connected to the same place that the panel
meter uses--but that's really a side issue. As the scenario was
described, the voltmeter was pegged at 18 volts--you can't say from that
that the resulting voltage was 18 max; it's more like 18 min.

Excellent observation.

Bob . . .


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PostPosted: Sat Feb 18, 2006 9:03 am    Post subject: Over-voltage event w/ IR alternator Reply with quote

Hello Mr Lee,

I know it's probably a long shot, but is there any chance that the
failed alternator/regulator could be recovered for further examination?
I'd pay shipping to have it sent to someone for failure analysis.

I'll extend this offer to anyone else that has an alternator/regulator
failure on an IR system.
Regards,

Matt-
bob(at)flyboybob.com wrote:

Quote:


Yesterday morning on the way to church I noticed the alternator idiot light
come on. A quick check of the volt meter indicated 18 volts. I was driving
my son's 1990 Ford F-150 with an IR alternator. It took me about thirty
seconds to figure out what to do. There was not enough time left before
church to make a forced landing so I kept flying. I started turning on
anything electrical to absorb the extra electrons that were smashing the
battery. When I remembered the off road driving lights my son recently
installed and turned them on I was down to 13 volts. The voltage would
varry with RPM and as long as I kept everything on and the RPM below 1500 I
could keep the voltage under 14 volts. As the truck accelerated away from a
stop and the transmission was in lower gears the idiot light would come on
each time the voltage was above 16 volts which happened around 2000 RPM.
Once in high gear the RPM would settle around 1200 and the voltage would be
around 13 volts.

In thirty years of driving I would guess that I have had five or six
alternator failures. This is the first time it has been a high voltage
failure. All of the other times it has been low output failures.

Conclusions:
1. some IR alternators out there will detect an overvoltage event (turn
on the idiot light) and yet do nothing about it (continue to produce 18
volts).
2. one event does not make conclusive scinece
3. a check list for OV events would have solved this problem quicker - I
need a plan for low frequency failures with simple solutions.
4. z-13 would have handled this problem in my airplane as the main
alternator would have tripped the OV module; the low voltage tone in my
earphones would alert me to turn on the standby alternator and flight would
have continued to destination.
5. what I learned from conclusions 1, 3, and 4 is worth the risk of
starting another IR alternator e-mail flood.
6. I'm glad I removed the IR regulator from my plane's alternator and
replaced it with an external unit and OV module.

Just remember, everything I say could be wrong - or right?

Regards,

Bob Lee
KR2 N52BL
91% done only 63% to go!









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PostPosted: Sat Feb 18, 2006 11:26 am    Post subject: Over-voltage event w/ IR alternator Reply with quote

Matt Prather wrote:

"... is there any chance that the
failed alternator/regulator could be recovered for further examination?"

As a student of the AeroElectirc Connection, I know that the repeatable
experiment and it's resulting data is the only way to understanding.
Unfortunately I have misplaced my DVM and have not been able to find it.
The truck is parked in the barn waiting for me to fix it. Until I can find
my DVM and do some experiments I'm happy to let it sit there.

I will supply feedback when it is available. As far as testing the
alternator, it depends the core charge associated with the replacement.

Regards,

Bob Lee
KR2 N52BL
91% done only 63% to go!


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PostPosted: Sat Feb 18, 2006 12:05 pm    Post subject: Over-voltage event w/ IR alternator Reply with quote

Great!

I am interested to hear what you find.

I'll cover the core charge if need be.
Regards,

Matt-
bob(at)flyboybob.com wrote:

Quote:


Matt Prather wrote:

"... is there any chance that the
failed alternator/regulator could be recovered for further examination?"

As a student of the AeroElectirc Connection, I know that the repeatable
experiment and it's resulting data is the only way to understanding.
Unfortunately I have misplaced my DVM and have not been able to find it.
The truck is parked in the barn waiting for me to fix it. Until I can find
my DVM and do some experiments I'm happy to let it sit there.

I will supply feedback when it is available. As far as testing the
alternator, it depends the core charge associated with the replacement.

Regards,

Bob Lee
KR2 N52BL
91% done only 63% to go!









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