EFIS backfeeding a dead bus

[diablouser]

My RV-10 system will have duel Skyviews.  It will also have an "Endurance" bus with important loads and a normal bus with the majority of loads.  If the charging system goes bad or the Master relay fails, the endurance bus is switched directly to the battery and the normal bus switched off to reduce loads.  (The aircraft will use fuses so pulling breakers is not an option.)  The endurance bus is normally fed with a diode from the normal bus.

If one Skyview  is on the endurance bus and the second on the normal bus:

1.  Will any of the common lines, Serial port, GPS, audio, dimmer or contacts backfeed an unpowered display?

2  Should backfeed blocking diodes be installed in the unpowered display power lines?

Thank you

Bruce Patton



The endurance bus is diode isolated

 

[dynonsupport]

SkyView is fully designed for redundancy, so there is no issue with one screen off and the other on.

One consideration is to have backup batteries, in which case the second screen won't turn off when the power goes away when you switch to the backup bus.

 

[diablouser]

It will have backup batteries for both displays. The question is not answered.

Restated. Can the any of the connections to the powered display, such as SP, GPS etc, backfeed the unpowered display's bus power inputs (pins 1 & 20)? In other words could the powered display provide a "sneak" connection to the dead bus whichwould have several devices on.

 

[dynonsupport]

No, no power from the SkyView that is on will end up coming out of pins 1&20 on the SkyView that is off. The system was explicitly designed to operate in the setup you have described.

 

[diablouser]

Thanks. 

I asked because many years ago when I was doing Startup testing at a Nuclear Power station, we had a device that was powered from two sources.  It worked just fine until someone had the power selector switch set at "both"  and depowered one of the 4KV busses feeding the device.  The hot bus tried to power all the dead bus loads via some circuitry/wires in the device.

The flash,  flames and smoke were something to behold!

Bruce Patton

 

[Battson]

Related question - if we have a total power failure, and one Dynon unit (in my case D100) is powered by a battery pack (internal Dynon battery), will it be able to access network functions through associated Dynon units which do no have a backup battery supply (e.g. D120) for items which are plugged into the DSAB networked unit?

I presume "no" is the answer, but it never hurts to ask!

 

[Dynon]

If the other units aren't receiving their own external power, then their functions won't be available. The EDC is powered by the D100, however.

In contrast, in SkyView, SkyView Network provides power to anything on the D9 SkyView Network connectors, except the servos. So a battery backed up SkyView display won't lose its ADAHRS, EMS, etc.