AC ESSENTIAL DISTRIBUTION - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General

AC Essential Distribution - Block Diagram ** ON A/C NOT FOR ALL

The AC essential distribution network corresponds to busbars 4XP (115 VAC ESS bus) and 8XP (115 VAC SHED essential bus) and their associated sub-busbars.

** ON A/C NOT FOR ALL

2. Component Location

AC Essential Distribution - Component Location

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
** ON A/C ALL
5XH	A/XFMR-115/26VAC, ESS		125	24-52-51
8XH	CNTOR-AC SHED ESS BUS	106VU	125	24-52-55

** ON A/C NOT FOR ALL

3. Operation
The AC essential distribution network can be supplied:

either by 115 VAC BUS1 1XP,
or by 115 VAC BUS2 2XP in case of loss of power from main busbar 1XP (in this case, the crew has to select ALTN on AC ESS FEED pushbutton switch to recover 115 VAC ESS BUS),
or by the emergency generator in emergency configuration or smoke emergency configuration,
or by the static inverter in emergency configuration during RAT extension and when the CSM/G is switched off after landing.

The major part of this network is supplied with three-phase 115 VAC/400 Hz.
A 115/26 VAC single-phase autotransformer, identical to those of the main distribution supplies an essential 26 VAC/400 Hz sub-busbar (431XP-A).
In case of loss of supply of 115 VAC ESS bus and 115 VAC SHED bus, a warning is triggered on the ECAM

AC Essential Distribution - ECAM Warnings ** ON A/C NOT FOR ALL

115 VAC SHED BUS - Upper and Lower ECAM Display Unit ** ON A/C NOT FOR ALL

Loss of the 115 VAC ESS BUS (Class 1 - Level 2) ** ON A/C NOT FOR ALL

NOTE: Part of this network (115 VAC SHED bus 8XP) is automatically shed in emergency configuration when the static inverter is operating.

The AC essential distribution-network can be supplied by:

115 VAC BUS1 1XP
115 VAC BUS2 2XP, if there is a loss of power from main busbar 1XP (then, the crew must select ALTN on the AC ESS FEED pushbutton switch to make 115 VAC ESS BUS serviceable again), or
The emergency generator in emergency configuration or smoke emergency configuration, or
The static inverter in emergency configuration during RAT extension and when the CSM/G is switched off after landing.

The largest part of this network is supplied with a three-phase 115 VAC/400 Hz.
A 115/26 VAC single-phase autotransformer, same as those of the main distribution, supplies the essential 26 VAC/400 Hz sub-busbar (431XP-C).
If there is a loss of supply of 115 VAC ESS bus and 115 VAC SHED bus, a warning comes into view on the ECAM

AC Essential Distribution - ECAM Warnings ** ON A/C NOT FOR ALL

115 VAC SHED BUS - Upper and Lower ECAM Display Unit ** ON A/C NOT FOR ALL

Loss of the 115 VAC ESS BUS (Class 1 - Level 2) ** ON A/C NOT FOR ALL

NOTE: Part of this network (115 VAC SHED bus 8XP) is automatically shed in the emergency configuration when the static inverter operates.

[Rev.10 from 2021] 2026.03.31 23:24:56 UTC