[shiney]

in planning my system, I am considering an Avionics bus (this thread is not about the pros and cons of the Avionics bus!). On Z-11, the main bus to e-bus has a diode in the feed, if I added an avionics bus and the feed from the e-bus, would I need a diode between them or is one diode sufficent?

Thanks


Shiney

 

[Mike S]

The way you describe it, the avionics buss is a sub function of the E buss, and only one diode is required.

Just be sure the diode is rated to handle the total load from both buss's.

Good luck.

 

[shiney]

Will do

Thanks Mike, I thought that was the answer.


Martin

 

[Mike S]

I assume you are running dual batteries, aux batt is feeding the "E" buss direct???

 

[shiney]

diode

In early planning stages yet, but considering weight issue probably single battery (VFR only in UK/Europe).


Martin

 

[Mike S]

Without going out to the hangar, and getting Nuckkols book, I just dont remember the layout of the Z11 schematic.

The usual reason to isolate an "E" buss through a diode is to prevent the aux power source from backfeeding to the non "E" stuff, if something goes wrong with the main power, while allowing the main batt to feed the "E" buss through the diode during normal opps.

The diode is like a one way check valve for the current flow.

Sorry to be a bit pedantic, just want to be sure you understand what is going on here.

Go recheck the Z11, see if there is a diode in a single batt configuration.

 

[apatti]

Go recheck the Z11, see if there is a diode in a single batt configuration.

Yes, Z11 does have a diode to isolate the E-bus. If your E-bus draws more than 3-4 amps continuous, a heat sink is recommended.

 

[shiney]

heatsink

Yes, I have heatsink with my diode.

 

[Mike S]

I just got through looking at the diagram again.

The diode is there to prevent backfeeding power to the main buss, when; 1. the alternator fails, and 2. the main is switched off, and 3. the "essential buss alternate feed" switch is on.

In this case, the circuit is pretty close to what you would have with a dual battery setup-------only here the single batt is supplying the power to each of the two feed sources, thus the need to isolate the "E" buss with a diode for when you are on (the equivalent of) aux power.

Long winded was of saying you should be fine if you follow the plan.

Just realize the "essential buss alternate feed" switch must be manually activated if you have an in flight need for "backup" power to the "E" buss.

Good luck.