Paul Stewart wrote:
> 1. If (as I intend to) I use OV protection via a relay and 5A c/b,
> can I do away with an alternator/generator output switch and pull the
> c/b when I want to deliberately take the alternator off line (don't know
> when that would be)?
Good example of where to use a pullable breaker. If used as a switch, the
Potter&
Brumfield W23 is rated for 10,000 cycles, similar to others.
BTW re OV, the Rotax regulator schematic I now have tells me she's cleverly
fail-safe
(zero/low output when the most likely components fail - the ones that get
hot). The ones which could cause OV do low-current duty, and as the case of
any similarly trivial DC circuit the probability of failure of component failure
is extremely remote. Nevertheless, always your choice.
> 2. Where exactly have folk attached engine block grounding straps?
I used one of the black engine mount bolts. Tested good with 'Lectric Bob's
handy
milliohmeter kludge. Starter doesn't draw a lot anyway.
> 3. What do folk use and where does one get the 30A slow blow fuse
> required for battery feed and alternator/generator feed to the main bus?
Time/current curve on automotive fusible link (Littlefuse MAXI) is pretty much
same as a 3AG glass slow-blow (which they still make in 30A, BTW).
> 5. I don't quite follow why, if there is a requirement for the trim
> motor to be wired directly off the battery rather than the bus bar, the
> same is not true of at least one of the 914 fuel pumps - surely these
> are as much if not more flight critical than the trim motor?
Will it ever happen that you might park the aircraft and leave the fuel pump
running?
As to flight critical, if one were to seek FAA certification here, there's
no way they'll approve w/o redundant electrical systems for the 914. Running
one direct off the alternator output is the best one can do with one electrical
sys.
However, if you do have OV protection, one pump connected that way poses a
serious
safety hazard in the even of an OV trip. This was debated in a thread some
time back.
> 6. I intend to wire using fuses rather than c/b ( OV protection
> excepted) - is there anything other than this which 'must' be protected
> by c/b rather than fuse?
Motors are good candidates for CB's, e.g., tri-gear flap motor, but some
production
aircraft mfr's use a fuse there for even bigger motors.
> 8. Am I correct in thinking GPS antennas con 'see' through fibreglass?
Yes.
Reg,
Fred F.
|