Failure of the External Power Because of an Unbalance

TASK 24-41-00-810-830-A
Failure of the External Power Because of an Unbalance

1. Possible Causes

feeders
external power

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
ASM 242202
ASM 242203
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 244101

3. Fault Confirmation
Subtask 24-41-00-860-070-A ** ON A/C NOT FOR ALL

A. Test
(1) Energize the aircraft electrical circuits from the external power AMM 24-41-00-861-002.

4. Fault Isolation
Subtask 24-41-00-810-092-A ** ON A/C NOT FOR ALL

A. If it is not possible to connect the external power source to the aircraft electrical network and if the fault symptom is identified by the CFDS message EXTERNAL POWER UNBALANCE:

do a check of the feeders for a short circuit or a short to ground ASM 244101, ASM 242202 and ASM 242203 between:
. the external power receptacle (20XG) and the EPC (3XG)
. the EPC and the primary circuit breakers of the AC main buses 1XP and 2XP through the BTC 1 (11XU1) and the BTC 2 (11XU2)
do a check of the status of the primary circuit breakers of the AC main buses 1XP and 2XP.

(1) If the feeders are not correct or if the primary circuit breakers are open:

repair or replace the feeders as necessary
close or do a reset of the primary circuit breakers.

(a) Energize the aircraft electrical circuits from the external power AMM 24-41-00-861-002.
1 If it is not possible to connect the external power source to the aircraft electrical network:

replace the external power .

(2) If the feeders are correct or if the primary circuit breakers are closed:

replace the external power .

Subtask 24-41-00-860-071-A ** ON A/C NOT FOR ALL

B. Test
(1) Energize the aircraft electrical circuits from the external power AMM 24-41-00-861-002.
(2) De-energize the aircraft electrical circuits from the external power AMM 24-41-00-862-002.

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