DC ESS BUS AIRBUS
 

When there is DC 1 BUS fault, the DC2 BUS supplies DC 1 BUS via DC BAT. But does the TR ESS comes automatically to supply DC ESS BUS and what is the use of TR1 then? Thanks

Yes it does.

TR 1 will be doing nothing and if DC Bus 1 is being powered from DC Bus 2 via the DC Bat bus then presumably DC Bus 1 itself is fine and the most likely reason why it had to be powered this way is because TR 1 itself has failed.

This is for the A320 anyway.

Thanks for your reply! I really wanted the answer on the Airbus fleet, so once again thank you! Just to reconfirm: does the TR ESS comes automatically to supply DC ESS BUS or is there any button?
AF330

No worries. Yes, it's automatic if its just a TR failure.

If it was due to AC Bus 1 failing on some older A320s you need to press the AC ESS feed button which will power the AC ESS Bus from AC Bus 2 and consequently the DC ESS Bus via the ESS TR. But on newer ones even that's automatic. But that's a different fault to your original question anyway.