VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #1  
Old 11-11-2019, 08:45 PM
avrojockey avrojockey is offline
 
Join Date: Aug 2019
Location: Appleton, WI
Posts: 46
Default Question for AEC Z11 Mod for E-Bus

Electrical novice needing help...

My RV-9A does not have an E-bus (endurance/essential), just a switched Battery Bus (master switch) and a Avionics Bus, switched through an avionics switch. All circuits are protected with hard-to-get-to-but-still-inflight-accessible fuses.

If IMC I want the ability to kill power to everything but the essentials to isolate shorts while aviating and communicating...near impossible to do in the current configuration, certainly not quickly while maintaining aircraft control. The new E-bus will have CBs or easily accessible fuses.

I'm using Z11 schematic as a starting point, but I want to change a couple things...see pictures...changes are in red.
  1. I removed the Hot Battery Bus because all I need is the E-Bus feed
  2. I removed the Diode and replaced it's function with the STDP switch thats ON/ON, so the E-Bus is fed by the normal switched Battery Bus OR directly from the battery. This will be a guarded switch.
  3. Increased to 14AWG wire to handle greater load requirements and longer wire runs.

Is there anything I'm missing? Is the diode still required? Do I need further protection somewhere? Will this kill me?

Thanks!
Tim


__________________
Tim Holmes
Appleton, WI
ATP, CFI/II/MEI
RV-9A N904DC
Reply With Quote
  #2  
Old 11-11-2019, 09:15 PM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 2,940
Default

In your revised circuit, a diode is not needed because there is no way
for current to flow from the E-Bus to the main power bus.
-
Fuses isolate shorts. No pilot action required.
-
Can it kill you?
What if the 10 amp breaker trips? There is a reason that the main power bus is not protected by a fuse or circuit breaker.
That long 14 AWG wire connected to the battery is always hot. It could make sparks and ignite spilled fuel after a forced landing.
A pilot should have the ability to shut off all electrical power at the source.
__________________
Joe Gores
RV-12 Flying
Reply With Quote
  #3  
Old 11-12-2019, 07:49 AM
avrojockey avrojockey is offline
 
Join Date: Aug 2019
Location: Appleton, WI
Posts: 46
Default

Quote:
Originally Posted by Mich48041 View Post
What if the 10 amp breaker trips? There is a reason that the main power bus is not protected by a fuse or circuit breaker.
Most of the components powered by the E-Bus have dual power inputs with internal diodes, so if the 10A CB pops then the short is in that
circuit and I can repower the Main Power Bus? Is this rational? I was just going by the original Z11 design has a 7A fuse protecting the E-Bus
I just increased the load with the wire gauge.

Quote:
Originally Posted by Mich48041 View Post
That long 14 AWG wire connected to the battery is always hot. It could make sparks and ignite spilled fuel after a forced landing.
A pilot should have the ability to shut off all electrical power at the source.
What if I change the SPDT switch to a DPDT to also control an added S704-1 relay forward the firewall similar to the Z13/8 design?
This would eliminate the long run of live 14AWG unless you needed it in an emergency. If things got bad, prior to forced landing
the E-Bus switch would be killed in addition to the Battery Master.
__________________
Tim Holmes
Appleton, WI
ATP, CFI/II/MEI
RV-9A N904DC

Last edited by avrojockey : 11-12-2019 at 07:56 AM.
Reply With Quote
  #4  
Old 11-12-2019, 09:23 AM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 2,940
Default

Bob's E-Bus was intended to supply power to a small essential load, thus 7 amps. Essential means
different things to different people. Many builders connect loads that are essential to them but
not to others. I would increase the essential bus circuit breaker size to at least 20 amps.
An E-Bus relay will allow the pilot to shut off power near the battery.
__________________
Joe Gores
RV-12 Flying
Reply With Quote
  #5  
Old 11-14-2019, 03:33 PM
avrojockey avrojockey is offline
 
Join Date: Aug 2019
Location: Appleton, WI
Posts: 46
Default

Thanks for the input, Joe
__________________
Tim Holmes
Appleton, WI
ATP, CFI/II/MEI
RV-9A N904DC
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 07:49 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.