Buses

Also from: Electrical Buses

Can be supplied by the engine driven generators (GEN 1 and GEN 2), APU generator (APU GEN), external A or B (EXT A and EXT B), and emergency generator (EMER GEN) powered by the green hydraulic system.

Both EXT A and EXT B are required to power all buses and galleys.

The emergency generator is in the main wheel well. If required, it takes a few seconds to come online, during which time the batteries power the buses.

AC 1 → AC ESS (via a contactor)

AC 1 → TR 1 → DC 1, DC BAT

AC 2 → TR 2 → DC 2

AC 1 → ESS TR → DC ESS

AC 1

Supplies AC ESS, TR 1, DC 1, DC BAT. If AC 1 fails, there is an automatic reconfiguration leading to AC 2 supplying AC ESS.

AC 2

Supplies TR 2, DC 2, APU TR, DC APU.

AC ESS

Supplies ESS TR, DC ESS.

DC BAT

Charges the batteries. Can supply DC ESS in a failure of AC ESS.

DC APU

Charges the APU battery which is dedicated to starting the APU.

Other buses

AC ESS SHED, DC ESS SHED: shed when insufficient power exists
AC LAND REC, DC LAND REC: buses that power systems required for an approach and landing
SHED LAND REC: a bus that is shed when the landing recovery buses are energised
HOT 1, HOT 2: hot battery buses from battery 1 and 2