Today's Message Index:
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1. 06:11 AM - Re: stacking ring terminals on terminal post (Robert L. Nuckolls, III)
2. 11:52 AM - How does the Ducatti rectifier/regulator work? (user9253)
3. 12:08 PM - Re: How does the Ducatti rectifier/regulator work? (Robert L. Nuckolls, III)
4. 02:21 PM - Re: How does the Ducatti rectifier/regulator work? (Robert L. Nuckolls, III)
5. 04:43 PM - Re: How does the Ducatti rectifier/regulator work? (C&K)
Message 1
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Subject: | stacking ring terminals on terminal post |
At 22:49 2014-12-18, you wrote:
These discussions on how many connectors on a single bolt caused me
to recall an accident that a good friend was in. It was a large
46,000 lb. Army Boeing CH-47 Chinook helicopter. The helicopter had
8 fuel boost pumps distributed in 6 tanks to pump the fuel up to the
engine driven pumps. The helicopter was lost when both of the
turbine engines flamed out due to fuel starvation (not fuel
exhaustion). All of the 8 boost pumps had the ground wires connected
to one bolt. The bolt did OK, but due to vibration, the sheet metal
it was anchored in failed and the bolt broke free of the airframe
mount and thus the ground was lost to all of the fuel pumps. Boeing
learned from that and soon had 4 ground bolts with the wires
distributed between them, and a connector bus between all 4
bolts. It was a single point failure that had been overlooked by the
design engineers.
History has shown us a few lessons where rather simple design
features were overlooked by very talented designers.
Bottom line, there is more to this question than just how many
terminals may be connected to one bolt.
I have seen several references to single point failures in these discussions.
Food for thought.
Jim . . . .
This illustrates the value of the FMEA. Don't suppose
or calculate anything . . . assume the worst down
to the fundamentals . . . the simple ideas.
All those books full of rules-of-thumb are the
top-layer attempt to avoid unhappy circumstances
that can arise from an inability to look down into
the layers of potential failure.
I don't recall ever reading some words on bonding
and/or limits to terminals on studs suggesting,
"Oh, by the way, make sure that the thing you're
bolting to isn't going to break/burn off as a
consequence of stresses not addressed by this
rule."
The universe runs on physics. A huge puzzle
of patterns that under ideal conditions, fit
together with permanence and functionality.
Most cases of a puzzle piece jammed into a
less-than-best-fit is of little or no
consequence. But sometimes, a 'hit' on the
extreme end of the bell curve can cause the
assembled puzzle to fall apart . . . and
it's always a surprise.
The artful component of our science is to be
curious, cognizant and competent observers
of how the most rudimentary of puzzle pieces
have been assembled in the past . . . as
a study in both success and failure. It's
this knowledge of lessons-learned that offer
foundation for future successes and minimizing
risks in new adventures.
In this endeavor, you cannot have too many
observers nor is any intellectual exploration
without value. This is how the potential for
unhappy surprises are first resolved intellectually
sitting at our keyboards . . . thus minimizing
the risk of surprise at 5,000 feet . . . or
on short final to the rocks.
See: http://tinyurl.com/mwjbzt3
Bob . . .
Message 2
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Subject: | How does the Ducatti rectifier/regulator work? |
A fellow RV-12 builder asked me this:
> From the the little that I have read concerning dynamos, they operate at full
output all the time as they have no field current controlling them.
> Does that mean that if one runs the strobes and landing light all the time, the
Ducati reg/rectifier will have less heat to dissipate through the cooling fins,
and perhaps stay cooler and last longer?
I do not know the answer, thus am asking the experts on the AeroElectric List.
How does the Rotax 912 rectifier/regulator work? Does it short out the dynamo
output to control voltage? Or does it add a series resistance to drop the output
voltage? Or what?
Thanks, Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=435942#435942
Message 3
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Subject: | Re: How does the Ducatti rectifier/regulator work? |
At 13:51 2014-12-20, you wrote:
>
>A fellow RV-12 builder asked me this:
> > From the the little that I have read concerning dynamos, they
> operate at full output all the time as they have no field current
> controlling them.
> > Does that mean that if one runs the strobes and landing light all
> the time, the Ducati reg/rectifier will have less heat to dissipate
> through the cooling fins, and perhaps stay cooler and last longer?
>
>I do not know the answer, thus am asking the experts on the
>AeroElectric List. How does the Rotax 912 rectifier/regulator
>work? Does it short out the dynamo output to control voltage? Or
>does it add a series resistance to drop the output voltage? Or what?
>Thanks, Joe
>
>--------
Back 'in the day' when pm alternators were first being
added to small bikes, the electrical output on the order
of 5 amps did not offer a very challenging energy management
problem. Earliest regulators simply used an SCR triggered
on each of the alternator's half-cycle to simply short the
AC output when the waveform was 'high enough' . . . this
crude regulation philosophy caused the alternator to operated
in a max-power-output mode all the time . . . with excess
power being dissipated in the alternator's windings and
the SHUNT mode, rectifier/regulator's heat sink.
As the alternators go bigger and consumer design goals
for more sophisticated electrical systems grew, there
was a pretty popular shift to SERIES mode regulation.
The B&C R/R products have always used this philosophy.
The Ducatti regulators favored by Rotax were of this
general design as well . . .
http://aeroelectric.com/Pictures/Regulators/Rotax-Ducati_Rectifier-Regulator.jpg
There are more modern versions of this design that
use MOSFET transistors in the power control loop . . .
designs that dissipate much less power as heat.
Bob . . .
Message 4
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Subject: | Re: How does the Ducatti rectifier/regulator work? |
At 13:51 2014-12-20, you wrote:
A fellow RV-12 builder asked me this:
. . . From the the little that I have read concerning dynamos, they
operate at full output all the time as they have no field current
controlling them.
True, FULL output voltage, but not necessarily full
output POWER. It's the job of the rectifier regulator
to tailor the wild-frequency, wild-voltage AC into
some reasonably stable output at the desired voltage.
Bob . . .
Message 5
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Subject: | Re: How does the Ducatti rectifier/regulator work? |
Can we assume that 820E and 2E2 resistors in the schematic are 820 ohm
and 2R2 (2.2) ohm resistors?
Ken
do not archive
> http://aeroelectric.com/Pictures/Regulators/Rotax-Ducati_Rectifier-Regulator.jpg
>
>
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