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sportav8r(at)aol.com
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mprather(at)spro.net
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nuckollsr(at)cox.net
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 Posted: Wed Aug 02, 2006 7:28 am Post subject: Z-diagrams moved?? |
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Too fast on the keyboard . . . got 'sent' before I was finished.
--------------------------------------------------------------
Here's an earlier post on the subject of PM starter "run-on"
--------------------------------------------------------------
>I have a problem I need advice on. My electrical system is from an older
>version of Bob's drawings but fits the current Z-11 drawing pretty closely
>with a Z-22 substitution for the way I wire the starter run on relay. I
>need to replace the S704-1 relay which has gone bad. Can I use a standard
>starter contactor in place of the smaller lighter relay? It seems that
>the wiring logic should be the same regardless of whether the smaller or
>larger relay is used.
>Thanks in advance.
Looking over Z-22, I see that I've stubbed my toe. In the
article on spike catcher diodes:
http://aeroelectric.com/articles/spikecatcher.pdf
I alluded to the first issue of an AD against the ACS510
genere' of off-l-r-both-start key switches wherein the
FAA took note of EXTRAORDINARY energy dump from modern
light weight replacement starter solenoid/contactors.
See:
http://aeroelectric.com/articles/strtctr.pdf
Seems the coil de-energizing spike was eating up starter
control contacts in the switches (just like it did in
cars! . . . funny thing about that physics stuff . . .
same rules apply everywhere).
The first issue of the AD put a spike catcher diode in
the wrong place . . . but was modified some time later
to correct the error.
Then came along a new characteristic in modern, light-weight
replacement starters. Efforts to reduce starter push
button wear with an add-on starter contactor (a la Z-11
and B&C recommendations), we noted that the back-emf generated
during spin-down of a PM starter would cause a delayed retraction
of the starter's pinon gear when the push button was released.
We STILL didn't want to run full contactor coil current
through the panel control so a heavy-duty (30A) relay
was suggested and described in Z-22. However, making
the relay a "heavy duty" device did NOT alleviate the
need for spike suppression at the contacts. The heavy
duty relay was just as vulnerable to damage from
stored energy as the off-l-r-both-start key switch.
However, while concentrating on the run-on issue, I
overlooked the need for a spike catcher.
I've updated Z-22 and published it in the Page-Per-System
drawings at:
http://www.aeroelectric.com/PPS/Engine/Starter/PM_Starter_w_RunOn_Relay.pdf
Here's a good example of how the diode bridge rectifier
assembly can be used to good electrical and mechanical
advantage. I show two of the four didoes used to suppress
the spike out of the starter contactor -AND- the
relay coil. Further, the mechanical characteristics of
this part give us good places to bring pairs of wires
into the same terminal as tie points.
You COULD replace the S704 with a HEAVIER duty still
device like a starter contactor, but it's not necessary.
Try the NEW Z-22 and see what it does for you.
Bob . . .
| Quote: | >There's a link on this page:
>
>http://aeroelectric.com/whatsnew.html
>
>This one:
>
>http://aeroelectric.com/articles/Rev11/AppZ_R11J.pdf
>Regards,
>
>Matt-
>
> > Can't find 'em online anymore... link broken?
> >
> > I'm trying to have a discussion about PM starter run-on with another
> > fellow, and it's hard if I can't cite my sources 
> >
> > Thanks for any pointers to the reference docs.
> >
> > -Bill B
> > ________________________________________________________________________
> >
>
>
>--
>No virus found in this incoming message.
>
>-- incoming mail is certified Virus Free.
>Checked by AVG Anti-Virus.
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
--
No virus found in this incoming message.
-- incoming mail is certified Virus Free.
Checked by AVG Anti-Virus.
|
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
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