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Old 08-11-2017, 01:58 PM
leok leok is offline
Join Date: Apr 2013
Location: Clarkston, MI
Posts: 435
Default Electrical Design and Build continued

Much of the design flows out from these early choices. i.e. Choosing to use the VPX-pro as the ECB system drives many other features. Among other capabilities the VPX has 32 assignable power outputs and 10 assignable input switches. That means that any of the 32 power outputs (think circuit breakers) can be assigned to any of 10 switches (or left always on) to be switched individually or in assigned groups. Because of this capability I divided my avionics into 3 groups each addressed to one of the three switches. I can unload the avionics from electrical system stepwise in 3 quick steps or individually. I chose 3 groups, because I have 3 power levels: 1) primary alternator of 60 amps 2) backup alternator with 30 amps and 3) E Buss with 15 amps direct feed from the battery. The E Buss bypasses the VPX and master contactor and feeds directly from the battery. If the primary alternator fails, switch to BU alternator and turn off tertiary avionics. If the secondary alternator fails, turn on E Buss and turn off secondary avionics. I then have critical instruments using minimum power consumption to get me on the ground. This also works well in reverse for a phased start-up of the avionics. I have the physical switches co-located so the switching is quick and easy without hunting.


Each of the other 7 switches feed other groups, individual high current draws such as Pitot heat, or small fuse panels that in turn feed grouped functions such as interior lighting, exterior lighting, heated seats etc.


Each of the small fuse blocks I designed as sub-systems that are wired independently tied in only with the power feed from the VPX.

For example, I wanted rather extensive interior lighting. This comes from years of flying with the terrible lighting in certified aircraft, and many years in automotive engineering with good lighting. I have reading lights at each seating position, red and white instrument panel lights. I have RGBW (color adjustable lighting) for under glare shield lights, overhead, foot-well, switch tip and switch label back lights. All are LED and all are dimmable. These all feed from one small fuse panel controlled by one VPX switch with individual switches for each item.


Exterior lighting is the similar with navigation, strobes, wig wag, landing, taxi and tail beacon. These are switched as a single VPX power feed, with individual switches for each item.

Boarding lights come on when the doors are opened. I have a small battery direct, un-switched feed that has an override for when the doors need to be open for extended periods. I also feed several USB charge ports (to charge a phone at Oshkosh without the master on).
Building started Oct 5th 2014, Flying since 1/16/2020
RV Hotel, come by and visit if you're in town
Dues paid 2020

Last edited by leok : 06-25-2018 at 03:19 PM.
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