|Posted: Wed Jun 13, 2018 7:55 am Post subject: Sequence for bringing alternators on line.
At 10:09 AM 6/13/2018, you wrote:
Are your assertions below, about the SD-8, also valid for the SD-20 (now BC-410H)?
Any alternator . . .
I've been working with engine driven power sources on
aircraft and ground based vehicles for a long time. I've
spent hours in the lab with various alternators and generators
on test stands exploring system performance of the
various components with some pretty illuminating
Not once have I observed any adverse behaviors of
these machines when turning on or off EXCEPT for
the classic, uniquely AUTOMOTIVE definition of a
LOAD DUMP. This is a carefully orchestrated
condition where the system loads are low to zero.
The alternator is working hard to RECHARGE a
DEPLETED battery. The BATTERY becomes disconnected
from the bus.
This is the electronic equivalent of playing tug-of-war
wherein both sides have their heels dug in and are
straining on the rope . . . then you cut the rope
. . . EVERYBODY hits the ground.
I could duplicate this condition in a Bonanza or
Baron where the alternator(s) and battery are
on separate switches. Discharge the battery,
crank with ground power, turn on the alternator(s)
and then turn the battery off. Sho' 'nuf . . . you're
going to get a big bump in alternator output
due to a predictable delay in voltage regulator response
to a sudden drop in load wherein the BATTERY's
mitigating influence on such events is not present.
Now, how often and under what circumstances would
such an event happen in YOUR airplane?
Bob . . .
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