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  #31  
Old 06-08-2020, 10:40 AM
supik supik is offline
 
Join Date: Mar 2014
Location: Bratislava, Slovakia
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Quote:
Originally Posted by Mich48041 View Post
Isn't the E-Bus switch normally shut off and E-Bus current flows through the diode?
-no, normally the ESS BUS is powered from it's own relay and diode feed is there only in case the ESS BUS relay fails open

Quote:
Originally Posted by Mich48041 View Post
If that wire shorts to the firewall, battery current will cause smoke or fire.
Take a look at an ANL data sheet. A 35 AMP ANL will carry 80 amps indefinitely without
blowing. How many amps will the E-Bus normally draw? I think that a 35 AMP is adequate.
-rating makes sense, the idea of protecting the bus is priority -valid point. but this does not eliminate the case when the B lead shorts to the firewall and ALT 1 keeps running. You still have fumes or fire until you kill the ALT, at least you don't loose the ESS BUS, I take that.

Quote:
Originally Posted by Mich48041 View Post
What happens if the "B" lead shorts out? Does the 50 amp circuit breaker trip
before the ANL blows? Or does the diode smoke? Do any of Bob N's diagrams
have the aux alternator connected directly to the E-Bus?
-main ESS feed is through the ESS Relay; the 50amp CB shouldn't trip before the ANL does. If it does, it can be reset (1time), by that time ANL should have melted already as ESS BUS still fed from relay. Diode is rated up to 100A.

The split backbone allows for big fault isolation, thus should either part -MAIN or ESS develop a fault/short, I could possibly isolate the wrong side and land asap without loosing all systems.

Quote:
Originally Posted by Mich48041 View Post
Why have a 50 amp breaker? The E-Bus is not going to short out if properly installed.
ESS BUS max load is 30A + possible batt recharge, so that 50A breaker is there to protect the diode, rating is to prevent nuisance trips & isolate the MAIN BUS should the ESS BUS develop a total failure.

AVIONICS BUS is a requirement by local authority (I live in Europe) and my preference as well. The risk of total avionics loss is split between two AVIONICS BUSES (MAIN and ESS).
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Last edited by supik : 06-08-2020 at 10:42 AM.
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  #32  
Old 06-08-2020, 08:23 PM
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johnbright johnbright is offline
 
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Location: Newport News, Va
Posts: 390
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Quote:
Originally Posted by supik View Post
John,

I think I have the same setup as suggested by Bob N. unless I missed something? -except the Right Mag is not grounded (Left Mag (SureFly) is not impulse coupled). And I have omitted the BO pole by mistake but this one is not connected to anything either.

New PDF link: OM ELA Basic Electr Scheme v.32

Here is another guide from B&C which corresponds to Bob's setup + MOV across the S pole. https://bandc.com/wp-content/uploads...501-3_fig4.pdf
Hi Egor,

My observations are:
  • Surefly will be your engine start magneto, conventionally on the left as you show. Surefly retards timing for start and provides high energy spark, no need for right mag to be impulse coupled.
  • If right magneto is not impulse coupled, it should be locked out during start by adding jumper to Gerdes switch between R terminal and its adjacent GND terminal.
  • The central GND terminal of the Gerdes switch should be connected to the mag wire shields only, not to ground of the airframe.

I was able to view the pdf this time but I can't download it so I use the jpg. Oftentimes jpg is not detailed enough but this one is.
.
.
.
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  #33  
Old 06-09-2020, 12:54 AM
oren_rokach oren_rokach is offline
 
Join Date: Dec 2018
Location: Tel-Aviv Israel
Posts: 191
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Hi Igor,
Which Diode did you use for the Deuce diode?
standard schotkky?
or very low dropout FET driven equivalent such as:
https://media.digikey.com/pdf/Data%2...FS/SPV1002.pdf


Quote:
Originally Posted by supik View Post
John,

I think I have the same setup as suggested by Bob N. unless I missed something? -except the Right Mag is not grounded (Left Mag (SureFly) is not impulse coupled). And I have omitted the BO pole by mistake but this one is not connected to anything either.

New PDF link: OM ELA Basic Electr Scheme v.32

Here is another guide from B&C which corresponds to Bob's setup + MOV across the S pole. https://bandc.com/wp-content/uploads...501-3_fig4.pdf
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  #34  
Old 06-10-2020, 05:20 AM
supik supik is offline
 
Join Date: Mar 2014
Location: Bratislava, Slovakia
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Quote:
Originally Posted by oren_rokach View Post
Hi Igor,
Which Diode did you use for the Deuce diode?
standard schotkky?
or very low dropout FET driven equivalent such as:
https://media.digikey.com/pdf/Data%2...FS/SPV1002.pdf
Hi Oren,

I used this one combined with a heatsink bought from PerihelionDesign.com

http://www.farnell.com/datasheets/13...203.1587563607
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  #35  
Old 06-10-2020, 05:27 AM
supik supik is offline
 
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Location: Bratislava, Slovakia
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Hi John,

thank you, good catch! I will use a jumper between R and and the adjacent GND.

I am using an ACS key switch and according to their schematics the center GND terminal(5) should be connected to nearest structural member.

under Notes:
C. Use SHIELDED wire on all connections and ground shielding to nearest structural member.

http://acsproducts.co/wp-content/upl...ng-Diagram.jpg


Quote:
Originally Posted by johnbright View Post
Hi Egor,

My observations are:
  • Surefly will be your engine start magneto, conventionally on the left as you show. Surefly retards timing for start and provides high energy spark, no need for right mag to be impulse coupled.
  • If right magneto is not impulse coupled, it should be locked out during start by adding jumper to Gerdes switch between R terminal and its adjacent GND terminal.
  • The central GND terminal of the Gerdes switch should be connected to the mag wire shields only, not to ground of the airframe.

I was able to view the pdf this time but I can't download it so I use the jpg. Oftentimes jpg is not detailed enough but this one is.
.
.
.
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  #36  
Old 06-12-2020, 03:45 AM
supik supik is offline
 
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latest version v.33 with suggested updates:

https://i.ibb.co/hK4cR7Y/Diagram-OM-ELA-Igor-v-033.jpg
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  #37  
Old 06-12-2020, 10:46 AM
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johnbright johnbright is offline
 
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Posts: 390
Default I would ask Bob on Aeroelectric List about keyed start switch ground connections

Quote:
Originally Posted by supik View Post
... I am using an ACS key switch and according to their schematics the center GND terminal(5) should be connected to nearest structural member.

under Notes:
C. Use SHIELDED wire on all connections and ground shielding to nearest structural member.

http://acsproducts.co/wp-content/upl...ng-Diagram.jpg
Hi Egor,

I believe the ACS switch and the Gerdes switch Bob Nuckolls speaks to in "MagnetoSwitchOptions.pdf" are the same or functionally the same. You could ask Bob on Aeroelectric List about the ground connections.
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  #38  
Old 06-14-2020, 06:07 AM
supik supik is offline
 
Join Date: Mar 2014
Location: Bratislava, Slovakia
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Quote:
Originally Posted by johnbright View Post
Hi Egor,

I believe the ACS switch and the Gerdes switch Bob Nuckolls speaks to in "MagnetoSwitchOptions.pdf" are the same or functionally the same. You could ask Bob on Aeroelectric List about the ground connections.


John,

You were right! Thx!

Here is Bob?s answer to my question:

There is no BENEFIT for connecting to ground locally . . .
but there is RISK for damaging p-lead shields due to
starter currents flowing in a ground-loop situation.
Wire per examples in the z-figures where shields are
terminated at the mags and NO grounds are added at
the switch(es) whether a o-l-r-b-s keyswitch or
toggles.
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  #39  
Old 06-16-2020, 07:59 AM
supik supik is offline
 
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Default v.34

latest version v.34

https://i.ibb.co/NmqVgWx/Diagram-OM-ELA-Igor-v-034.jpg
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  #40  
Old 06-17-2020, 03:10 PM
Raiz Raiz is offline
 
Join Date: Nov 2009
Location: Cambridge, UK
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I really like the general concept with a high integrity essential bus that can be fed from the main bus, the battery and its own alternator. But, at a detailed level...

1. Have you considered placing the ANL 35 fuse between the battery contactor and the essential bus contactor. If you did that, you could use a smaller wire than 6 AWG for the feed to the ess bus and you could replace the ess bus contactor with a 40 amp relay - both worthwhile weight savings and also a useful reduction in the current consumption.

2. The ess bus backup feed has a 50 amp breaker on it, so the diode would need be capable of taking whatever the breaker lets through, so 50 amps continuously and probably rather more. If we assume a forward voltage of 0.5 volts, 50 amps will generate 25 watts of heat, which is a big heat sink (around 5" x 5" x 1" at a guess). Are you sure you need all those amps?

Raiz
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