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Z-11 I think

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Mark(at)wessonair.com
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Posted: Wed Sep 05, 2012 5:38 am Post subject: Z-11 I think

I am in the process of  designing the electrical for my RV-9 build and have a few questions. I think I  started with the Z-11 drawing but have made so many small changes using a little  of each that I don't know what to call it at this point. However I am using a  single alt. with an E-Bus.

 Would I be better off with  a E-Bus relay rather than a switch only? Seems better to have the wire running  all the way to the swith as a ground only rather than a hot there and  back.

 During normal flight  operation is the E-Bus switch left on so that power is direct rather than  through the diode. The diode seems inefficient since it generates  heat.

 Why are all the drawings  showing the simple on-off switches as on-on S700-1-3 rather than the  1-2?

 I am sure I will have  additional questions as I progress.

  

   

Mark  Wesson<?xml:namespace prefix = o ns  = "urn:schemas-microsoft-com:office:office"  />



  

   [quote][b]

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nuckolls.bob(at)aeroelect
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Posted: Wed Sep 05, 2012 8:09 am Post subject: Z-11 I think

 	  Quote: 	
		  However I am using a single alt. with an E-Bus.


	


 	  Quote: 	
		  Would I be better off with a E-Bus relay rather than a switch only? 

Seems better to have the wire running all the way to the swith as a 

ground only rather than a hot there and back.


	


   If your total e-bus loads can be supported through

   the 7A fuse, then that size of always-hot feeder from

   the battery bus does not violate legacy design goals

   for crash safety.



   Adding the relay is fine too . . . except that it

   adds a parasitic load on the order of .15 A . . .

   and one of the goals for the e-bus was to minimize

   if not eliminate such loads. But it's your choice

   commensurate with your own design goals.



 	  Quote: 	
		  During normal flight operation is the E-Bus switch left on so that 

power is direct rather than through the diode. The diode seems 

inefficient since it generates heat.


	


   No. Consider the operating requirements for power

   in every device qualified for commercial aircraft.

   The device must perform down pass battery-dead voltage

   levels (9V in a 14v system). When the alternator is

   running, main bus is 14.2 or better which puts the e-

   bus at 13.6 or so . . . nice source. When the alternator

   is off, the MAX voltage available to anything in the

   airplane is what ever the battery will provide . . . 12.5

   volts and DOWN.



   Hence the suggestion that a slightly depressed e-bus

   is not an operational concern. Now, if your e-bus

   is configured for HOURS of operations battery only

   (hopefully equal to or greater than duration of

   fuel aboard) then the e-bus loads are small . . . 3-6

   amps. 6 amps droped across a diode is about 4 watts

   of heat . . . insignificant when a 40-60 amp alternator

   is providing a 500 to 750 watt source of operating

   power.



 	  Quote: 	
		  Why are all the drawings showing the simple on-off switches as on-on 

S700-1-3 rather than the 1-2?


	


   You can go buy 1-2 if you like. I used to stock the 1-3

   which serviced both purposes and to keep line-items

   of inventory low, I suggested that the 1-3 was a good

   choice for BOTH slots both in terms of my inventory

   and your spares.

   Bob . . .

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Mark(at)wessonair.com
Guest

Posted: Wed Sep 05, 2012 11:22 am Post subject: Z-11 I think

The bis question now is what should I put on the E-Buss.

I think I can survive without a GPS or Xpndr.

I do think I want my Coms and NAV and since that is a SL-30 I will leave the

430W off.

Then my back-up Dynon D-6 draws very little.

I can power up the audio as is is cheap power. This leaves me with



E-Buss

Garmin GMA 240	540 MA (at) 13.8v = 7.5 watts	1A Fuse



Garmin SL-30	Com					5A Fuse

			Nav					3A Fuse



Dynon D-6		1A (at) 13.8v = 13 watts		1A Fuse

Total max 10 Amps which seems like smaller than the 7A for the E-Buss

without relay.

Am I missing anything essential on the E-buss?

I am not sure I would want this on a 7a fuse though.



??

			 

Mark Wesson

President / Owner



mark(at)wessonair.com

Ph   # 407-831-5061

Fax # 407-831-2570

http://www.wessonair.com

 



--

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bicyclop(at)pacbell.net
Guest

Posted: Wed Sep 05, 2012 12:45 pm Post subject: Z-11 I think

Or you can leave that stuff on the E-bus and turn       any of them off with their own power switches if you think you       need to save power. That gives you the flexibility to choose what       you want to use when the alternator is down. I lost the alternator       once, turned off the master, and flew on with two portable gps       (powered from E-bus), transponder, Dynon D10, and an electronic       ignition for a total of about 4 amps. Landed at a towered airport       (with com turned back on), gassed up, started the engine, turned       off the main bus, took off, turned off the radio, and flew on for       a total of about 3 1/2 hrs and an engine start after the       alternator failure. The next day still I had enough juice for an       engine start after I had replaced the alternator. This was on a       Concorde RG25.

       

       As far as E-bus switch position goes, I take Bob's point that the       diode voltage drop is insignificant for the electronics, but I       like to have the E-bus on so that I don't have to worry about       which switch goes first when the alternator fails. If I happen to       turn off the main bus before I turn on the E-bus, my electronics       will re-boot. The feed path from the diode should of course be       checked regularly so an E-bus switch failure can't ruin an       otherwise groovy day. I also don't have to       do any math to see the true bus voltage.

       

       Pax,

       

       Ed Holyoke

     

     On 9/5/2012 12:21 PM, Mark Wesson wrote:     [quote]       [quote]--> AeroElectric-List message posted by: "Mark Wesson" <Mark(at)wessonair.com> (Mark(at)wessonair.com)  The bis question now is what should I put on the E-Buss. I think I can survive without a GPS or Xpndr. I do think I want my Coms and NAV and since that is a SL-30 I will leave the 430W off. Then my back-up Dynon D-6 draws very little. I can power up the audio as is is cheap power. This leaves me with  E-Buss Garmin GMA 240	540 MA (at) 13.8v = 7.5 watts	1A Fuse  Garmin SL-30	Com					5A Fuse 			Nav					3A Fuse  Dynon D-6		1A (at) 13.8v = 13 watts		1A Fuse Total max 10 Amps which seems like smaller than the 7A for the E-Buss without relay. Am I missing anything essential on the E-buss? I am not sure I would want this on a 7a fuse though.  ?? 			    Mark Wesson President / Owner  mark(at)wessonair.com (mark(at)wessonair.com) Ph   # 407-831-5061 Fax # 407-831-2570 http://www.wessonair.com    --

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