Today's Message Index:
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1. 07:52 AM - Re: Too many Circuit breakers.... (andymeyer)
2. 09:42 AM - Re: Re: Too many Circuit breakers.... (Charlie England)
Message 1
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| Subject: | Re: Too many Circuit breakers.... |
Bob,
Great find on the LR3 voltage sense. I need to double check where I have that installed
right now.
Ignitions: No real monkey motion... primary is dual feed (battery and main alternator.)
Main alt dies, flip on the SD8 and turn off the master to load shed...
No rush.
Master dies, flip on SD8 and master off.
Fan ever stops: Ign#2 to EMER. (Boldface)
Major electrical issue (had an electrical fire in the F16). Shut master off and
ignition 2 to EMER. Fan keeps running - everything else is off.
Lightspeed design recommendation is to have the ignitions wired to the battery
side of the master. Help me understand what wiring the ignitions to the alternator
side of the master buys? I'm getting rid of a relay, switch, and a few connections
(and with the 3 position switch, get an isolated power source to keep
the fan running).
Power on EBus: 2.6 amps for two ignitions. 1.45A for GDU/GSU, AV30 is .5A, Eng
Mon ~.5A, IFD can and will be shut off as it pulls 4.9A, but is there to get me
in crappy IFR conditions onto the ground - turn it on for the approach. Landing
light only on short final. What do you suggest as a target for draw on the
EBus with an SD8?
I'm still one fuse, one switch for each ignition direct to the battery. One switch
has an additional position for an additional power source.
Boost pump - Multiple failures in one flight? I'm carbureted. Maybe I'm missing
something and should move this to the EBus.
Flight endurance - It's a Long EZ - 13 hours isn't abnormal.
I have mostly fuses, but pullable breakers for the things I want to be able to
hard shut off... A/P (obvious), audio panel(failed / squealing, etc...), transponder
(formation), and my home built engine monitor (to be able to reset it in
case).
I have some legacy W31 breakers for landing light, boost pump, exterior lights
and pitot heat. Am I better replacing those with a good carling switch and a fuse?
Thanks!
Andy
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=507984#507984
Message 2
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| Subject: | Re: Too many Circuit breakers.... |
I have a 'FWIW' general observation about electrical systems design
discussions that we have on this list/forum. (Some of us get email;
others use the forum, and stuff often doesn't 'translate' well between
the two formats.)
The rise of multiple variations of electronic ignition and/or computer
controlled, high pressure fuel delivery, the replacement of steam gauges
with glass, and the increase in the number of people flying homebuilts
in the IFR environment, has made these discussions much more difficult.
Examples:
VFR & 'traditional' engine & panel? minimal effect on electrical system
design
electronic ignition only (carb/mech injection fuel delivery)? minimal
effect on electrical system design
high pressure electronic fuel injection? HUGE effect
IFR? quite serious effect, especially with a glass panel
And I've probably forgotten other factors that significantly influence
electrical system design.
I constantly see people post a question without a complete listing of
what will be installed, and how the plane will be operated. I also
frequently see answers that overlook one or more of the above qualifiers
even though it had been mentioned earlier.
I wonder if it would help to have a list of installed appliances &
intended mission requirements at the top of every post when we're
discussing 'best practices'.
Last, for 'switchology', some stuff has to change, especially with
electronic injection, etc, but I tried to keep it as close as possible
to operating like a traditional a/c setup. It's bad enough for me to
reprogram myself, but if someone else ever needs to fly my plane, I fear
that a completely alien switching process would make it unsafe for them
to operate it, especially in an emergency.
Charlie
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