REFLECTOR: electrical question

[Alex Balic]

Hi Andy-

 

I guess it is good that you just have one “master” hence the name- and can
re-energize the essentials if you have a problem- my ECU runs independently
from the battery buss off of a 10 amp breaker (everything else is fused)
also- then you only need to remember to turn off just one master at the end
of the day- the reason it came to light was that I was checking voltages,
and got lower voltage on everything that was connected to my e-buss- the
diode feed caused a ½ volt drop across it- not a huge deal, but if I lost
generation ability on both of my alternators (not likely but never say
never)  then the e-buss would become unusable by the electronics connected
to it prematurely- but then I would have the alternate feed, which carries
effectively no resistance- and the battery buss gets powered before the big
contactors which seem to draw significant power on their coils just to stay
engaged- so by closing the master you can shed them too. I guess that is the
logic behind that- but thought I would check with everyone

. 

 

 

  _____  

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Andy Millin
Sent: Monday, June 29, 2009 1:57 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: Re: REFLECTOR: electrical question

 

Hey Alex,

 

Ahhhhh the subtleties.  I remember asking this same question when I was
looking at the diagrams.

 

I don’t believe the answer is earth shattering or super profound.  I believe
it allows us to setup the system so, under normal circumstances (main bus
on, e-bus off), if you have a catastrophic failure, like smoke in the cabin,
you have one switch to just shut it down.  If you set it up so the e-bus is
no longer a subset of the main bus and you have to run with both switches on
all the time, then you will have to remember to shut them both off.

 

I’ll review my notes when I get home.  If I find another reason, I’ll be
sure to pass it along.

 

Andy

 

 

 

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Alex Balic
Sent: 06-29-2009 12:08
To: reflector at awpi.com
Subject: REFLECTOR: electrical question

 

I suppose I should just ask the aero-electric board about this, but the
communication over there is not as direct as on the reflector- and we have a
bunch of good electrical guys on here. 

I have set up my 2 battery, 2 alternator electrical system as in the
aero-electric schematics with the Essential/endurance/emergency bus fed from
the main bus through a diode on one side, and when needed, by the battery
bus with a normally open “alternate feed” contactor on the other side. I was
just looking at this yesterday for some reason, and I could not fully
understand the purpose of this  setup- the function of it is to normally
power the E-bus through the diode off of the main bus, then if there is an
emergency, you can shut off the main buss loads with the master switch, and
energize the e-buss from the battery buss using the e-buss alternate relay.
My question I suppose is why not just run the e-buss off the battery buss
using a separate e-buss “master” switch, and avoid the entire diode
connection altogether. Then if you need to shed the non-essentials, just
turn off the master, and keep the e-buss switch on- I just could not get the
need for the diode connection to the master buss

.. maybe someone can
enlighten me

..

 

Alex

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20090629/1aacbe61/attachment-0001.htm>