Today's Message Index:
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1. 12:31 AM - Re: AeroElectric-List Digest: 4 Msgs - 08/13/13 (Franz Fux)
2. 09:23 AM - Re: Alt field ckt breaker tripping (Robert L. Nuckolls, III)
3. 09:27 AM - Re: Alt field ckt breaker tripping (jpkarnes@comcast.net)
4. 11:56 AM - Re: Alt field ckt breaker tripping (jpkarnes@comcast.net)
5. 04:08 PM - Re: Alt field ckt breaker tripping (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: AeroElectric-List Digest: 4 Msgs - 08/13/13 |
unable to respond to any mail until the 20th of August,
Message 2
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| Subject: | Re: Alt field ckt breaker tripping |
At 12:40 PM 8/13/2013, you wrote:
>Hi all,
>
>
>The engine and its electrical system has flown for over 100
>hours. The battery is a brand new 12V 18AH gel battery. The plane
>has not flown for over a year while some modifications/upgrades have
>been undertaken. The only difference is the installation of a
>secondary ignition system ala Paul Messenger's dual dizzy setup. I
>really doubt that there is a short to ground that is causing this
>problem. Do you recommend installing an external voltage regulator
>and if so, which one? Clearing this latest hurdle is the only thing
>keeping me from getting airborne again. :o)
>
>
Okay, good data. We know this is a change from previously
satisfactory operation. The battery is relatively new
and not likely to be 'soggy' such that it contributes
to system instability.
A automotive shop has pronounced the alternator as
righteous so it seems there is little probability
of internal regulator failure. You can confirm by
running the airplane with a voltmeter on the bus
(preferably an analog meter with a needle) and
see that the voltage is not only in the ballpark
but not 'jumpy'. Of course, you need to disconnect
the OV module.
Once you have confidence in alternator performance
then attention turns to the ov module. It may well
be out of calibration. You can test it on the bench
with an adjustable power supply. If a current limited
supply, set for about 1A, if not, put an automotive tail
light bulb in series with the ov module.
Increase voltage very slowly until the voltage drops and/or
light bulb lights. The module should trip at more than 16.0
and less than 16.5 volts.
I wouldn't worry about flying without it. Using the crowbar
OV module on an internally regulated alternator offers
a false sense of security. There are failures internal
to the regulator that cannot be externally address
except with techniques like . . .
http://tinyurl.com/7z6yzv9
There are dozens of suitable regulators for external
control of an alternator. The problem is that you need
to open your alternator, ground one field brush, bring
other brush to outside world.
Let's get your airplane flying first and then talk
about how you're going to address over-voltage
events.
Bob . . .
Message 3
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| Subject: | Re: Alt field ckt breaker tripping |
The 5A field breaker needs to have ABSOLUTE control
over field excitation voltage. This generally
accomplished by some modification of the alternator's
internal wiring . . . like a PlanePower, or modified
for external regulation like B&C.
How do I achieve the state you describe above "ABSOLUTE control over field excitation
voltage."
This does not explain the symptoms you're seeing.
I didn't fine your email address in my sales records
which suggests you got the OVM from B&C.
I think I purchased the OVM from you; it was probably over 10 years ago...
If you like, you can send me the OVM and I'll make
sure it's calibrated correctly. This is the first
step toward understanding root cause for the trips.
How old is your battery and what size?
Battery is 12V 18AH gel battery...
Thanks so much for your help!!
John K.
Zenith 601HDS with Stratus Subaru engine
Message 4
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| Subject: | Re: Alt field ckt breaker tripping |
Bob, you made my day.=C2- The engine has never run better and I have adhe
red to just about every recommendation you=C2-gave in your manual.=C2-
I am an electrical neophyte and your input has been invaluable.=C2- I owe
you a debt of gratitude!!
John K.
Suquamish, WA
Zenith 601HDS w/Stratus Subaru/Ram heads
Message 5
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| Subject: | Re: Alt field ckt breaker tripping |
At 01:55 PM 8/14/2013, you wrote:
>Bob, you made my day. The engine has never run better and I have
>adhered to just about every recommendation you gave in your
>manual. I am an electrical neophyte and your input has been
>invaluable. I owe you a debt of gratitude!!
>
> '
Pleased to be of service. Fly comfortably . . .
Bob . . .
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