|Posted: Fri Jul 20, 2018 12:09 pm Post subject: Voltage regulator wiring with fault indication.
At 11:59 AM 7/20/2018, you wrote:
|--> AeroElectric-List message posted by: Matthew Schumacher <schu(at)schu.net>
I've been trying to figure out why Bob doesn't show the "I" terminal used in Z11.Â Looking further it seems there are multiple ways to wire a ford regulator:
So why not wire it the second way so that we have a alternator out indication?Â Someone please tell me what I'm missing.
Waayyyyyy back when, the first alternators to go onto Cessna
single engine aircraft used the same regulator as the 1965
Ford passenger cars and an a similar alternator. In cars, the
alternator's AUX terminal (fed from the center tap of a "Y-wound"
alternator stator winding) was connected to the regulator's "S"
terminal. Back then "S" meant "stator". The "I" termnial was feed
from the "ignition" switch through a light bulb.
That little current flow through bulb would 'tickel' the alternator
field with juse enough current to present a volage at the
alternator's AUX terminal but ONLY if the alternator was
turning. Hence, this light spoke more to broken belts on
the engine than it did to loss of electrical functionality
of the alternator.
When this decidedly automotive system was adapter to the airplane
at Cessna, the first systems went in like this:
Here, the "S" terminal became "switch" and the field
relay got power directly from the bus as opposed to the
AUX terminal. It no longer sensed rotation of the
alternator. The "I" terminal could have been used
to drive a light . . . but it was even less meaningful
than when used in cars . . . it would be dark any time
the field switch was ON whether or not the alternator
was actually producing power.
Electronic replacments for the electro-mechanical
regulators have modified functionality of the
"I" terminal somewhat . . . but it would take
some testing to understand it and incorporate
that functionality into your operations.
It's MUCH simpler and universally accurate to
incorporate ACTIVE NOTIFICATION OF LOW VOLTAGE.
This feature's utility is unambiguous. The
light CANNOT go dark unless the altenrator is
Bob . . .
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