ECU charge Airbus

[AF330]

Hi!
I was learning the FADEC system (ECU, HMU, VSV, LPTCC...). But I learnt that the generator of the ECU had to be charged. So 2 questions:

1) Is it charger with DC? DC ESS? DC BAT? ...
2) Is the DC BAT charged? Or is it energy coming from DC 1 only?

Thanks

[Fursty Ferret]

FCOM says magnetic alternator so presumably no field coils required.

Unless you're using the word "charged" in a strange way... If the internal generator is not supplying sufficient power to the FADEC, channel A will be supplied from the DC ESS BUS; channel B will be supplied by the BAT BUS and DC BUS 2 for engines 1 and 2 respectively.

[Amadis of Gaul]

Seems to me that by "charged" he means "powered".

[AF330]

Thanks,
Yes, I mean "powered", sorry!

"If the internal generator is not supplying sufficient power to the FADEC, channel A will be supplied from the DC ESS BUS; channel B will be supplied by the BAT BUS"

Ok, I get it till here!

DC BUS 2 for engines 1 and 2 respectively.

But what is powered by this?

Thanks

[Amadis of Gaul]

What is powered by what? What are you asking?

[Mecaniquito84]

Every FADEC control engine have a PMA, permanet magnet generator driven by corresponding engine gear box.
Long time did not work on 320, correct me is I'm wrong, but the logic is more or less:
At plane power up, FADEC will be powered by a/c system for a short time, then auto switched off since on ground FADEC, which is cooled by engine air flow, may overheats. Maintenance/Crew my bypass this by a dedicated FADEC test sw, for instance, to know is EGT is low enough for next flight or in other airbys, to check oil qty indication.

When eng is started, Fuel sw on, FADEC is again powered by a/c buses, at n2 =7% (repeat out of memory), PMA have enough rpm to generate power to FADEC removing a/c power bus from it. Should PMA fail, a/c power takes place till engine shut down, where you are AOG with a related mssg.

[AF330]

Thanks a lot! Got it!