List,
I've been working on the wiring diagram for my airplane (electric panel,
IFR, plane power internally regulated main alt and a SD-8 backup). So
I've been reading though Bob's book and am familiar with the Z-13 wiring
diagram, however there are a two things about it that I don't like:
1. It is possible to turn on both alternators at once. It is my
understanding that you don't want to have both alternators online at
once and I don't want the pilot to be able to cause damage by not using
the correct switches.
2. Alternate feed switches. Feed switches seem cumbersome since it
requires the pilot to know something about the electrical system.
I think I have a new wiring diagram that addresses these things, but I
want to run it past this list and perhaps Bob so that others can help me
find the problems.
Here is how it works:
The avionics bus is treated like the endurance bus since the avionics
are the only things I care about if my alternator fails (I have mags and
a mechanical fuel pump.) When the master switch is on, the battery
pulls the battery contactor which brings the main alternator and battery
into the system. Should something happen to the main alternator the
battery will continue to power the system unless I switch the ALT switch
to AUX. When the alternator switch is on AUX it takes out the main alt
and powers up the SD-8 wired up with the self exciting hack. This will
allow my aux alternator to power the avionics bus (when the Avionics
master is on AUX) but will keep my master contactor and battery separate
from the rest of the system. In the event that I want to charge my main
battery I can turn the master switch off which will then allow me to
charge my battery should I desire to try and bring the main alternator
back after a dead battery.
In order to clear up any confusion here are the basic switches,
settings, and mode of operation:
Master: on, Alt: main, Avionics: main; Normal operation running on the
main alternator and battery.
Master on, Alt: Aux, Avionics: Main; Aux alternator is online and master
alternator is offline, battery is powering everything.
Master on, Alt: Aux, Avionics: Aux; Aux alternator is powering avionics,
main alternator is offline, and battery is powering everything except
avionics.
Master off, Alt: Main, Avionics: main; Nothing is powered up.
Master off, Alt: aux, Avionics: main; Avionics are off, Aux alternator
is online and is charging the battery.
Master Off, Alt: aux, Avoinics: aux; Avionics are on aux alternator, aux
alternator is online and is charging the battery.
Perhaps it would be more intuitive if I name the switches like this:
Battery: On | Off (Aux Charge)
Alternator : MAIN | AUX
Avionics: MAIN | OFF | AUX
This setup reduces the panel down to 3 switches and gives the operator
good control over the system, allows for the battery to be isolated or
charged from the aux alternator, and gives a way for non critical
devices to run off the battery.
If this doesn't look sane to you please post some feedback. Any help I
can get is greatly appreciated.
Thanks,
schu
