REFLECTOR: Fusing distribution lines
Terry Miles
terrence_miles at hotmail.com
Tue Aug 1 07:39:11 CDT 2006
Keith, Dave,
Thanks for the great explanations. I didn't know that about the b lead
link being there to protect the alternator. I thought it worked like a
fuse in a circuit.
I am doing fuse blocks too, and trying to draw all this out on paper for
the sake of documentation and wire labelings. I have not started to
pull wire yet. It was only after getting into that paper process that I
saw that my choice to use auto fuse blocks as part of a bus power
control and distribution system caused me to have fusing built into my
distribution scheme.
I will have 3 battery related buses: a common (dual) batt bus, and
separate DC1 and DC2 buses. The batt are of equal size.
Overhead panel: I will run two (primary/backup) #18 wires on separate
10 amp fuses to power all the bus-switching switches up there. Example:
The overhead 700 2-1 toggle for selecting DC1 Hot or DC2HOT to be source
power to run ground avionics will feed juice to operate two (DC1 DC2)
relays. The Relays will then be used to connect up a 30 amp fused line
from the DC1 or DC2Hot fuse block and connect it up to the avionics
fuseblock feed screw terminal. (Or I could re-route this line direct
from the battery poles to the relay and skip the hot batt fuse block).
The fuse block it seems to me, will make the electrical maintenance and
documentation a lot cleaner even if it adds components. I can send you
a drawing. For alternator field on/off I am doing this: A toggle
likely a 700 1-3 (so I can power an "Alt Fld Off" annunciator). The
alt-fld-control relay power line will be a #20 5amp fused line from the
main bus but operated by a relay so I can utilitize my dual power feed
to the overhead and reduce the number of wires going up the conduit.
Make sense? I will try to send a pic of a drawer Hangar 18 Malcolm
Collier made for me. I am putting it in the lower right hand instr
panel to house all this stuff. That is still a WIP!! The drawer idea
actually comes from you Dave. For those who haven't seen it, Dave
Sharfenberg's cockpit config is a real eye catcher. The problem was
locating all these relays in limited space!
Another facit of this is annunciator LED's. I am not using switch
lights. For now it appears I will be powering some of these relays all
the time (even post shutdown) or pull the fuses out on my dual feed
lines for switching power on the overhead.
The Lasar timer came from Ed Kolwalski. He was an early RV8 builder and
sold his bird. I bought all kinds of tools and stuff from him as I got
started. The new owner of his RV didn't want any of it. It is in
Chicago right now and I am in Greenville SC. He checked w/ Unison and
they told him it worked on all models and engine types. I am happy to
send it to you when you need it. If it doesn't work---send it back. We
can work out a price. It is of no use to me, I just haven't gotten
around to putting it out on ebay. We have a common friend in Bill
Schlatterer off the GRT forum. Bill and I went to a Nuckol's seminar
together a year or two back.
Regards,
Terry
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Keith Hallsten
Sent: Monday, July 31, 2006 11:54 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: Re: REFLECTOR: Fusing distribution lines
Terry,
What are you using for your battery bus? I'm using a fuse block, so all
the feeders coming off it are protected, including the e-bus alternate
feed.
The decision regarding whether to protect the feeder to the e-bus
depends on whether there could realistically be a threat to that wire.
"Fat" feed wires do not have to be protected, provided that great care
is taken to avoid any mechanical threat and they are large enough to
support the maximum amperage that could actually be fed through them.
That's why the main #2 battery and ground cables don't need protection.
Similarly, if the grand total of all CBs or fuses coming OFF the e-bus
is significantly less that the amperage that the feed wire can sustain,
there is no real electrical threat to the e-bus wire. That's because
the other circuit protection would open before the feed wire could get
hot enough to be compromised. Naturally, this assumes that there cannot
be a short directly to the feed wire itself, which is where the care to
avoid any mechanical threat to that wire comes in.
The fusible link in the alternator "B" lead is to protect the alternator
from the battery, not to protect wiring from the alternator output. An
alternator is physically incapable of making significantly more amps
than it is rated for, and the "B" lead is sized to handle that
comfortably.
How did you end up with a spare LASAR timing box? I don't have one yet,
so I might well be interested.
Does anyone know whether there would be a problem using a separate
starter push button with a LASAR electronic ignition? All of their
documentation shows the classic "OFF - LEFT - RIGHT - BOTH - START"
keyswitch, but I would rather have the option to get the engine turning
before firing up the ignition. I don't know if the LASAR will be happy
starting on only one ignition, or coming alive when the engine is
already moving. I bought a starter pushbutton form B&C a few years ago,
before I was committed to the LASAR ignition, and I'd still like to use
it.
Keith Hallsten
_____
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Terry Miles
Sent: Monday, July 31, 2006 2:45 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: REFLECTOR: Fusing distribution lines
Keith, Al,
Thanks both of you for all the advice. Keith: If you haven't yet,
don't buy a timing device for that Lasar ignition system. I have one I
will sell you at half price.
Did either of you fuse your battery-fed-to-essential distribution
line--that is the wire running from your battery hot bus to the
emergency feed into your essential bus. I am doing this with a 700
series toggle switch that will control a 30 amp relay. I am just trying
to decide whether to put a say 40 amp fuse on the #10awg running from
the Hot Batt bus to the relay #30 lug and out the 87 to the essential
bus? What did you guys do? Obviously I am fusing my alternator feed
line with a fuseable link, but should I also fuse my Batt Only bus feed
lines in the event of a major component draw or short to ground or
whatever on the client bus?
Thanks
Terry
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Keith Hallsten
Sent: Monday, July 17, 2006 9:38 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: Re: REFLECTOR: Bus, Battery & Back Order
Terry,
Everyone will have their specific requirements, based on their
background and the way they intend to use their plane. Thus, what
others have done is a source of ideas, but ultimately not very relevant
to your own decisions.
I have ordered my plug-n-play panel from Stein Bruch. We are currently
exchanging drawings to get to final conclusions regarding exact
locations of equipment, switches, etc.
I went with the dual-display, single AHRS, GRT "Horizon" EFIS. I
seriously considered their "Sport" EFIS, but it was not actually
shipping at the time I placed my order (the last I heard it was to start
shipping today), and it isn't entirely clear that the way certain
functions are implemented will satisfy me. There comes a point in every
project when you have to "pull the trigger" on the order and at that
point you need to choose from equipment that is actually available.
For in-panel backups, I have a mechanical airspeed and altimeter and the
TruTrak "ADI Pilot 2" autopilot which provides attitude and bearing
information, even when the autopilot is not in use. I decided to put
the "handheld" G-396 backup GPS in a panel dock, which makes it a
"semi-panel-mount". That way I don't have extra wires to get tangled
in, and I can actually wire it up to the EFIS as well.
For the handheld backup comm radio I'm installing a panel jack to
connect to the second comm antenna in the other winglet and a "cigarette
lighter" style of power receptacle. This will back up the single SL-30
Nav/Comm in the panel.
I'm going to put in two batteries, mostly so that the LASAR ignition and
EIS 6000 engine monitor can run off a separate battery during starting.
I will determine the battery size after I have done the weight and
balance. Once the engine is running I will tie the batteries together,
so it won't be a true two-bus system. I will have an "endurance" bus,
though. Since I will have no vacuum system, I couldn't resist putting
an SD-8 dynamo on the vacuum pump pad.
I didn't like the design of the Velocity exhaust system that was
available at the time, so I got an exhaust system made to my
specifications by Custom Aircraft Parts of El Cajon, CA. Clint Anderson
shipped it to me less than a week after I ordered it, so backorder was
not an issue!
Keith Hallsten, XLFG
N585V (reserved)
_____
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Al Gietzen
Sent: Wednesday, June 15, 2005 10:36 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: RE: REFLECTOR: Bus, Battery & Back Order
Keith;
It sounds like we have taken a pretty similar approach to the panel.
Except I have digital electronic backups and no gauges.
I just completed all electrical, and checkout of the things in the panel
(Well; still some wire 'dressing' to do.) As far as I can check here on
the ground everything works (yippee!) - er, except the Trutrak AP.
I expect I'm an isolated case, but I have not been happy with it from
the start. Had to return the servo because it was sticking, and now the
programmer module isn't working. They are assuring me that they will do
whatever is needed to make things right; which I appreciate, but if I
were doing it over I would opt for the Trio EZ pilot. One reason is the
Trio servo gears disengage when the unit is off - the Trutrak unit
doesn't and puts some unnecessary drag on the controls.
I also have the SL-30, and put in an I-COM panel mount for a COM 2.
Inexpensive; and from what I've heard, they work fine. I think it is
basically a knockoff of an earlier King model.
Photo of panel attached.
Now to get busy on the interior.
Al (I'll probably run the engine tomorrow, haven't heard it for a few
weeks :-))
I have also been meditating on backup for the single-AHRS, two-display
GRT
EFIS. Although I may change my mind again, I am also settling on
mechanical
airspeed and altimeter. Therefore, I'll probably leave out the backup
airspeed and altimeter in the EIS - I'll talk to them at OSH next month
about the value of cross-check info to the EFIS. The GRT EIS 6000 will
be
the only source of engine instrumentation (loss of engine instruments is
a
nuisance, not an emergency). I plan to use either a TruTrak Pictorial
Pilot
or their upcoming ADI Pilot as the
autopilot-and-combination-backup-attitude-indicator. After that, the
backups come out of the flight bag!
I'm going with the internal GPS in the EFIS as the only panel-mount GPS
for
the first couple of "VFR only" years. I plan to leave a space for a GNS
430, but not install it until and unless I establish that I need the
additional capability the way I fly. I'll have a handheld GPS with
fresh
batteries up and running on cross-country flights.
I'm putting in a single SL-30 Nav/Com, and carrying a handheld comm
radio as
backup. I'm going to talk to the vendors at OSH about satellite weather
options - that seems like a pretty valuable capability in a
cross-country
airplane.
Keith Hallsten
(I mounted my straight heated pitot out the nose of the XLFG this week.
Looks cool!)
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Terrence Miles
Sent: Wednesday, June 15, 2005 12:27 PM
To: reflector at tvbf.org
Subject: REFLECTOR: Bus, Battery & Back Order
Hi to everyone but in particular to Brian, Keith, Al G, and Kurt who I
think
are deep into wire issues.
Here's what I got.
For Electrics: Here's my current plan and why. Two big batts in the
nose.
One stacked on top of the other. For now I am going to slap the ground
leads together and run them in parallel with B&C L60 alternator (60
amps)
and the B&C external voltage regulator and the o'volt protection.
I may one day with not a lot of effort, put in a 2nd aux battery
contactor,
but I see its practical value as limited due to what follows next.
I have decided in favor of a single power bus. I can't see a strong
enuf
reason to break things into separate buses to power up or shed in event
of
alternator problems. I will instead pull out a checklist and do a load
shed
procedure at each components control head/ panel switch/CB/whatever.
(Two
mags, by the way until I have her in the air and de-bugged)
When I re-read the Nuckols stuff on dual batt & single alt, I decided
it
wasn't for guys like me. I can put two equal amphr batts right side by
side...read no #2awg wires running all over hell. I don't have dual
EI's.
Sure as sh--t the day I loss a alternator would be the day the #1 comm
would
be TU and I have to repower the main load buss to access #2 comm and get
myself confused say 2 years down the road by which time all the electron
theory will be faded into dim memory.
GRT stuff: Single AHRS system, 2 screens, EIS in the radio stack, no
airspeed&Alt add-on to the EIS in favor of round dials below the GRT
screeens. Decided basically to abandon the two spare power leads. I am
told a solenoid controlled contact can draw an amp to 1.5 amps just to
hold
closed, and the diodes will cost you a volt in pressure.
Some of the above was driven by electrical abnormal checklist drafting.
Some from the local tower operator/Cozy guy/ex USAF avionics tech. For
backup, his personal philos is a bag of external hand helds.
What do you four think of this? Anybody else want to chime in?
I called Affordable panels this week. He is an RV vendor...uses the
Approach Hub stuff. He is very backed up. I am looking to make the
major
buy with Stein Air. Anybody have any comments on him?
Where's everybody else on this topic. Are you guys going to wire up
your
own intercomponents in the avionics rack?
Last but not least...anybody else waiting for engine mounts and exhaust
systems besides me??
Regards,
Terry
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