Today's Message Index:
----------------------
1. 06:13 AM - Re: Revmaster PM alternators (user9253)
2. 06:34 AM - Bent EGT Probe Acceptable? (jdubner)
3. 09:02 AM - Re: Revmaster PM alternators (dj_theis)
4. 06:39 PM - Re: Flaky EGT Probe (Art Zemon)
5. 06:45 PM - Re: Re: Dual Alternator "Failure" - SOLVED (Art Zemon)
Message 1
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| Subject: | Re: Revmaster PM alternators |
The purpose of a fuse in the alternator output circuit is to protect the battery
from short circuits. Alternator output is self current limiting. The quantity
of electrons flowing is limited by the ability of the magnets to push them.
There is no inductive voltage spike when a load is removed from the alternator.
The voltage will go up because the electrons being pushed by magnets have
no where to go. But the voltage is not induced by a collapsing magnetic field.
Alternator windings can fry due to overheating caused by inadequate cooling or
due to prolonged high current output. Electrically speaking, there are two
separate alternators. But both are contained in one physical enclosure. Operating
both alternators simultaneously at full output generates lots of heat which
could fry windings. The solution is to redesign the alternator with larger
wires and/or better cooling. Or limit the load. Or limit the total output
current by operating only one alternator at a time.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=490918#490918
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| Subject: | Bent EGT Probe Acceptable? |
Would it be permissible to bend an EGT probe as in the attached image and still
receive good service from it? This is for avoiding interference with the cowl
and other obstructions in a Long-EZ installation.
Thanks,
Joe
--------
RV-8A
Independence, OR
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=490919#490919
Attachments:
http://forums.matronics.com//files/bent_egt_probe_example_543.jpg
Message 3
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| Subject: | Re: Revmaster PM alternators |
Thanks Joe,
The purpose of a fuse in the alternator output circuit is to protect the battery
from short circuits. Alternator output is self current limiting.
I appreciate your feedback. The short circuit protection meant to protect the
battery was not something I had considered as the design intent. I Understand
the fixed current model of the PM alternator so what a damaged winding suggests
is a weak or less than robust design, as you imply.
If you noticed, the ignition circuits are part of the same flywheel assembly and
in neither of these cases did the ignition fail. This is evidence to me that
the self destructive heat generated by a stator winding was not high enough
to propagate the damage beyond the source of the heat (the physical relationship
is as the drawing shows, the ignition coils separate the alternator windings).
Now that I think of it, the 450 hour plane did have a previous incident where the
ignition coil failed and the smell he sensed when the alternator failed led
him to expect one of the ignition coils had failed again. Note, with none of
these failures did the engine stop running. The ignition coils are redundant.
One feeds the upper ignition and one feeds the lower.
I doubt I can obtain any forensic data on the failed systems but I will give it
a shot and see what might be learned.
My goal is to modify (improve) my engine charging system to avoid any of these
failures.
Thanks again for your feedback Joe. It helps a lot.
Dan Theis
Sonex 1362R[/quote]
--------
Scratch building Sonex #1362
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=490920#490920
Message 4
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| Subject: | Re: Flaky EGT Probe |
Bob,
The Lycoming operating manual says:
LEANING WITH MANUAL MIXTURE CONTROL. (Economy cruise, 75% power or less,
> without flowmeter or EGT gauge.)
> <snip>
> Fuel Injected Engines.
> (1) Slowly move mixture control from =9CFull Rich=9D position
toward lean
> position.
> (2) Continue leaning until slight loss of power is noted (loss of power
> may or may not be accompanied by roughness.
> (3) Enrich until engine runs smoothly and power is regained.
I tried this method and compared the results with using the EGT (also per
Lycoming's operating manual). I got the same fuel flow both ways.
I learned the manual method in airplanes that lacked an EGT probe on each
cylinder. It's quick and doesn't require me to interrupt my scan.
-- Art Z.
On Fri, Aug 16, 2019 at 1:18 AM Bob Verwey <bob.verwey@gmail.com> wrote:
> Hi Art
> So how is it that you dont use your EGT? To me it is a prized tool in the
> engine management arsenal!
>
> On Fri, 16 Aug 2019 at 05:03, Art Zemon <art@zemon.name> wrote:
>
>> Folks,
>>
>> One of my four EGT probes is flaky. Sometimes it works. Most of the time
>> it reads zero (too low to register). I don't actually use the EGT for
>> anything so I'm not very excited about spending money to fix it. But it
>> annoys me to see three nice green bars and one black space where there
>> should be a green bar.
>>
>> Are these things repairable?
>>
>> -- Art Z.
>>
>> --
>> https://CheerfulCurmudgeon.com/
>>
>> *Love the stranger for you yourselves were strangers in Egypt. *Deut.
>> 10:19
>>
>
>
> --
> Best...
> Bob Verwey
> 082 331 2727
>
>
--
https://CheerfulCurmudgeon.com/
*Love the stranger for you yourselves were strangers in Egypt. *Deut. 10:19
Message 5
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| Subject: | Re: Dual Alternator "Failure" - SOLVED |
You're so right, Joe.
And for anyone interested, here is the full write-up on my blog:
https://cheerfulcurmudgeon.com/2019/08/17/dual-alternator-failure/
Cheers,
-- Art Z.
On Wed, Aug 14, 2019 at 8:07 PM user9253 <fransew@gmail.com> wrote:
>
> The above situation reinforces the recommendation to have a separate fuse
> for each and every load, no matter how small or insignificant. Fuse are
> inexpensive.
--
https://CheerfulCurmudgeon.com/
*Love the stranger for you yourselves were strangers in Egypt. *Deut. 10:19
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