nuckolls.bob(at)aeroelect
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 Posted: Tue Feb 02, 2016 9:15 am Post subject: Automatic way to turn On the Standby alternator (was Diffe |
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At 05:33 AM 2/1/2016, you wrote:
| Quote: | Well, scratching my head about this thread, I came up with a brilliant idea on how to manage a 2-alternator system.
(most probably there were hundreds of other people, before me, who had the same idea�)
Let me put it out to you, anyway
According to the second option I made in my last post (below), flying normally with the MAIN ALT field switch On, and the BackUp ALT field switch Off. |
| Quote: | When the pilot is warned that no current is flowing from the MAIN ALT, he shall turn Off the MAIN ALT field and manually turn On the Backup ALT field.
How about designing a circuit that, when the pilot turns Off the MAIN ALT field, automatically the BackUp ALT field is turned On?
Ideas welcome!
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That's pretty much what the LR3C/SB1 combination does . . .
but the 'magic' is in the monitoring and annunciation
system built into the SB1.
You COULD simply use two LR3C regulators in a Z-12
style installation. But if your ship's loads are less
than 20A, then the failure would not be noticed.
The core ideas behind the SB1 called for annunciation
of the failure combined with a simple means for
prompting the pilot to reduce loads to under 20A.
This protcol is consistent with design goals in TC
aircraft to not allow a failure to go un-announced
-AND- to provide crew with information for keeping
stand-by alternator within rated limits.
This was necessary to smooth the STC process for
putting a Z-12 like system on a TC aircraft. We
have more latitude in OBAM aircraft . . . the
owner can install current instrumentation on the
s/b alternator, then run two LR3C regulators, both
set for 14.2, and leave the s/b system OFF in
normal ops.
Lost of main alternator would be annunciated by
LOW VOLTS warning whereupon the pilot moves a
couple of switches and monitors instrumentation
to do a load reduction.
After 40+ years of working in FMEA and cockpit
protocols, I am reluctant to automate much of
anything. Adding automation increases parts count.
It must be applied carefully such that some
automatic function doesn't hide useful/critical
information from the pilot. Last, it needs to
add value. If you're cruising along 200 miles
out of destination and the low voltage light
comes on, you have plenty of time to accomplish
a prudent response . . . finish your cup of
coffee. Making a 3-seconds-or-less run through
the flipping of switches will not have any
appreciable benefit for reducing risk in the
outcome of your flight.
Hence, my long repeated advice of keep it simple
to minimize cost of ownership, weight and
cockpit complexities that call for any other
pilot, particularly the next owner, to acquire
new understanding.
Electro-whizzies on the panel are constantly
driving up risk of distraction from operation
of the airplane. It has been the well seasoned
goal of airframe designers not to drive up
system complexities any more than absolutely
necessary . . . vagaries in fuel system
operations on Barons buried more than
a few propellers in the dirt . . . I think it
was the Aerostar fuel system that made for
several bad days in the cockpit too.
Bob . . .
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