If you lost your DC ESS Bus you would lose the CIDS so no PA Availability at all - comm’s with the cabin crew would also be lost.
LOSS of TRU 1 + 2 (AC Bus 1 + 2 loss) would mean no DC 1 BUS therefore no ACP 3 - But you still would need CIDS for PA.
The only way to lose DC ESS BUS would be if Battery 2 was either flat or turned off (above 50 knots you cannot switch it OFF - well you can but if it’s supplying the essential DC bus nothing will happen).
In other words it’s Airbus’ intention that the ESS DC BUS will always be powered no matter what the failure.
Hope this isn’t too much info … 😉
Last edited by aeo; 18th April 2022 at 06:12.