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nuckolls.bob(at)aeroelect
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 Posted: Sun Sep 23, 2018 6:11 pm Post subject: Fwd: Hello everyone , new here and need some help ! |
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| Quote: | Im building an Rv8 and would like to make it IFR with a Garmin g3x fit .
After reading the excellent online book Aeroelectric Connection i intend to use the system 13/8 with B&C parts . (Attached Diagram )
I however have a few questions , as my school boy electrics is struggling !
1)What happens to an Alternator ( in this case the SD- when it reaches its max current capacity , does it get hot and eventually blow , or does it just start decreasing its voltage output , eventually going below the battery voltage causing a current drain from the Batt ?
Yes . . . the bus simply sags until the
battery picks up the slack. Nothing smokes.
BUT . . . you should configure your ENDURANCE
loads to remain at or just below the maximum
output of the SD8 which is on the order of
10A. This is your en route configuration.
Then, when it's time for descent and approach
to landing, you can turn on all the goodies
and use SD8+battery to complete the flight.
This holds ship's battery energy in reserve
2) If its the former I'm thinking following a Main Alternator failure if the Aux Alternator is turned on ( without opening the main battery contactor ) maybe there is room to overload this too ? If so i was thinking maybe an improvement to this system would be an interlock that when the E-Bus and Aux Alt are activated they open the ground to the battery contactor coil and thus prevent an overload of the emergency system ? Maybe you could have a guarded 3 posn switch that on first click , opens the main battery contactor and closes the E-Bus Alternate feed , then second click closes the AUX - Alt feed relay ? A one switch saves the day sort of thing ??
Why so much monkey-motion? If the main alterantor
fails you get a low volts warning whereupon you
finish your cup of coffee before configuring
to endurance mode by:
E-Bus alt feed closed
DC PWR master OFF
Reduce loads on E-bus to 10A or less
if needed.
On descent and approach, delay bringing
any other electro-whizzies on for as long
as practical, then move DC PWR master to
BAT and continue normal ops to the
runway.
3) It would be nice to have a CAS message on my Garmin G3x that indicates if the SD-8 is functioning ok incase of a main failure . Im thinking of a “Standby Alt Fail “ caption that would indicate when ever the SD-8 is not producing power and ready for an emergency . What sort of output would an unloaded ( Supply relay open ) Sd-8 be producing ? unstable , high , low or on task at 12v?? How can i send a “I'm functioning ok and producing power “ signal ? Maybe a relay coil on its output that closes a signal to the G3X ?? ( see my hand drawing )
But maybe id need diode after that coil to ensure its only Aux Alt that can close it and not reverse supply ?? What would a Diode in the line do to supply voltage ?? How could i make it so the relay closes at 12ish volts ??
Any better ideas ??
Too many questions I know !
Thank you so much for any help !
Z13/8 is about the most reliable system
flying in light aircraft today. It's light,
low cost, has an excellent FMEA outcome
and no downstream periodic/preventative
maintenance for continued airworthiness.
If the G3X has a low voltage annunciation
feature, program it for about 13.0 volts.
That's all you need. |
Bob . . .
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nwparkinson(at)btopenworl
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| Posted: Sun Sep 23, 2018 11:12 pm Post subject: Fwd: Hello everyone , new here and need some help ! |
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Thank you Bob.
It’s great to have access to your thoughts. With your recommended actions below following a main alt failure, does this mean you recommend operating with the Aux Alt always turned on ? Or is this turned on in addition to selecting DC PWR Off and E-Bus Alt feed.
Out of interest what is the SD-8 output doing when the Aux Alt relay is open ? Does it produce a steady 12 , or float around if I was measuring it ?
Thanks again !
Neil
On 24 Sep 2018, at 03:10, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | | Quote: | Im building an Rv8 and would like to make it IFR with a Garmin g3x fit .
After reading the excellent online book Aeroelectric Connection i intend to use the system 13/8 with B&C parts . (Attached Diagram )
I however have a few questions , as my school boy electrics is struggling !
1)What happens to an Alternator ( in this case the SD- when it reaches its max current capacity , does it get hot and eventually blow , or does it just start decreasing its voltage output , eventually going below the battery voltage causing a current drain from the Batt ?
Yes . . . the bus simply sags until the
battery picks up the slack. Nothing smokes.
BUT . . . you should configure your ENDURANCE
loads to remain at or just below the maximum
output of the SD8 which is on the order of
10A. This is your en route configuration.
Then, when it's time for descent and approach
to landing, you can turn on all the goodies
and use SD8+battery to complete the flight.
This holds ship's battery energy in reserve
2) If its the former I'm thinking following a Main Alternator failure if the Aux Alternator is turned on ( without opening the main battery contactor ) maybe there is room to overload this too ? If so i was thinking maybe an improvement to this system would be an interlock that when the E-Bus and Aux Alt are activated they open the ground to the battery contactor coil and thus prevent an overload of the emergency system ? Maybe you could have a guarded 3 posn switch that on first click , opens the main battery contactor and closes the E-Bus Alternate feed , then second click closes the AUX - Alt feed relay ? A one switch saves the day sort of thing ??
Why so much monkey-motion? If the main alterantor
fails you get a low volts warning whereupon you
finish your cup of coffee before configuring
to endurance mode by:
E-Bus alt feed closed
DC PWR master OFF
Reduce loads on E-bus to 10A or less
if needed.
On descent and approach, delay bringing
any other electro-whizzies on for as long
as practical, then move DC PWR master to
BAT and continue normal ops to the
runway.
3) It would be nice to have a CAS message on my Garmin G3x that indicates if the SD-8 is functioning ok incase of a main failure . Im thinking of a “Standby Alt Fail “ caption that would indicate when ever the SD-8 is not producing power and ready for an emergency . What sort of output would an unloaded ( Supply relay open ) Sd-8 be producing ? unstable , high , low or on task at 12v?? How can i send a “I'm functioning ok and producing power “ signal ? Maybe a relay coil on its output that closes a signal to the G3X ?? ( see my hand drawing )
But maybe id need diode after that coil to ensure its only Aux Alt that can close it and not reverse supply ?? What would a Diode in the line do to supply voltage ?? How could i make it so the relay closes at 12ish volts ??
Any better ideas ??
Too many questions I know !
Thank you so much for any help !
Z13/8 is about the most reliable system
flying in light aircraft today. It's light,
low cost, has an excellent FMEA outcome
and no downstream periodic/preventative
maintenance for continued airworthiness.
If the G3X has a low voltage annunciation
feature, program it for about 13.0 volts.
That's all you need. |
Bob . . .
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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