Loss of the AC Essential Sheddable Busbar

TASK 24-50-00-810-802-A
Loss of the AC Essential Sheddable Busbar

1. Possible Causes

CNTOR-AC SHED ESS BUS [8XH]
RECTIFIER-AC SHED ESS BUS CNTOR [9XH]
wiring
C/B-AC/SHED/ESS BUS/CNTOR/CTL [1XH]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 24-00-00-810-803-A	Circuit Breaker Tripped and/or C/B TRIPPED Warning
AMM 24-41-00-861-002	Energize the Aircraft Electrical Circuits from the External Power
AMM 24-41-00-862-002	De-energize the Aircraft Electrical Circuits Supplied from the External Power
ASM 245201
AMM 24-52-55-000-001	Removal of the AC Shed Essential Bus Contactor
AMM 24-52-55-400-001	Installation of the AC Shed Essential Bus Contactor
AMM 31-60-00-860-001	EIS Start Procedure

3. Fault Confirmation
Subtask 24-50-00-860-052-A

A. Job Set-Up
(1) Aircraft Maintenance Configuration
(a) Energize the aircraft electrical circuits
AMM 24-41-00-861-002.
(b) Do the EIS start procedure (Upper ECAM DU and lower ECAM DU only)
AMM 31-60-00-860-001.

Subtask 24-50-00-865-051-A

B. Make sure that this(these) circuit breaker(s) is(are) closed:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	AUTO FLT/MCDU/1	11CA1	B01
49VU	LIGHTING/XFMR/115V.5V/ESS BUS	29LP	H03
122VU	LIGHTING/TST/BOARD/SPLY	30LP	X06

Subtask 24-50-00-710-052-A

C. Test
(1) Do this test:

ACTION	RESULT
1.On the ECAM control panel: push the ELEC key to get the ELEC page.	On the lower ECAM display unit: the normal configuration comes into view with the SHED indication shown in amber on the right of the AC ESS busbar. On the upper ECAM display unit: the AC ESS BUS SHED indication comes into view.
2.On the panel 11VU, on the MCDU1: Fully decrease the brightness of the MCDU screen (display off).	On the panel 11VU: the MCDU1 stays off.
3.On the panel 25VU: set the ANN LT switch to test:	On the panel 35VU: the IDG1, IDG2, GEN1, GEN2, BUS TIE and GALLEY pushbutton switches do not come on.

4. Fault Isolation
Subtask 24-50-00-810-051-A

A. If the test confirms the fault:

Do a check of the status of the circuit breaker (1XH)

(1) If the circuit breaker is closed:

Replace the CNTOR-AC SHED ESS BUS [8XH] AMM 24-52-55-000-001 and AMM 24-52-55-400-001.

(a) If the fault continues:

Replace the RECTIFIER-AC SHED ESS BUS CNTOR [9XH] .

(b) If the fault continues:

Do a check and repair the wiring between:
. the circuit breaker (1XH) and the pin A/3 of the rectifier (9XH) through the relay (16XE) and the contactor (2XB)
. the pin A/2 of the AC SHED ESS BUS contactor rectifier (9XH) and the ground
. the pin A/A of the rectifier (9XH) and the pin A/Z of the AC SHED ESS BUS contactor (8XH)
. the pin A/X of the contactor (8XH) and the pin A/Z of the rectifier (9XH)
. the pins A/1, A/5, A/7 of the contactor (8XH) and the first branch point
. the pins A/2, A/6, A/8 of the contactor (8XH) and the first branch point ASM 245201.

(2) If the circuit breaker is open:

Do the procedure (Ref. TSM TASK 24-00-00-810-803).

(a) If the fault continues:

Replace the C/B-AC/SHED/ESS BUS/CNTOR/CTL [1XH] .

Subtask 24-50-00-710-053-A

B. Do this test to make sure that the system operates correctly:

ACTION	RESULT
1.On the ECAM control panel: push the ELEC key to get the ELEC page.	On the lower ECAM display unit: the normal configuration comes into view.
2.On the panel 11VU, on the MCDU1: Adjust the brightness of the MCDU screen.	On the panel 11VU: the MCDU1 is ON.
3.On the panel 25VU: set the ANN LT switch to TEST.	On the 35VU: the annunciators come on with maximum brightness.

5. Close-up
Subtask 24-50-00-860-053-A

A. Put the aircraft back to its initial configuration.
(1) On the ECAM control panel, set the UPPER DISPLAY and LOWER DISPLAY potentiometers to OFF.
(2) On the MCDU1,
Fully decrease the brightness of the MCDU screen (display off).
(3) De-energize the aircraft electrical circuits
AMM 24-41-00-862-002.

[Rev.8 from Aug 2018] 2026.04.04 04:26:55 UTC