W DOC AIRBUS | TSM A320F

Failure of the Interlock Signal of the External Power

TASK 24-41-00-810-813-A
Failure of the Interlock Signal of the External Power

1. Possible Causes
  • external power
  • external power plug
  • wiring
  • RCPT-EXT PWR [20XG]
  • C/B-GND/PWR/PROT [2XG]
  • feeders
  • GAPCU [24XG]
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 244101
AMM 24-41-34-000-001
Removal of the Ground Power Control Unit (GPCU)
AMM 24-41-34-400-001
Installation of the Ground Power Control Unit (GPCU)
AMM 24-41-51-000-001
Removal of the External Power Receptacle
AMM 24-41-51-400-001
Installation of the External Power Receptacle
3. Fault Confirmation
Subtask 24-41-00-860-060-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 24-41-00-810-072-A ** ON A/C NOT FOR ALL
A. If the test confirms the fault:
  • stop the external power source,
  • disconnect the plug from the external power receptacle (20XG),
  • make sure that the ELEC/EXT PWR pushbutton switch (10XG) is in the ON position,
  • do a check of the external power plug for a short to 28VDC of the pin F.
   (1) If there is a short to 28VDC:
  • repair or replace the external power plug .
   (2) If there is no short to 28VDC:
  • do a check of the wiring of the external-power interlock control ASM 244101 for a short to 28VDC or a short circuit between:
    . pin F and pin E of the external power receptacle (20XG)
    . pin B/12E of the GAPCU and pin F of the external power receptacle (20XG).
     (a) If the check is not correct:
     (b) If the check is correct:
       1 If the external power energizes the electrical circuits:
  • stop the trouble shooting.
       2 If the external power does not energize the electrical circuits:
  • do the trouble shooting given in Para. 4B.
Subtask 24-41-00-810-073-A ** ON A/C NOT FOR ALL
B. If the external power does not energize the electrical circuits:
  • Do a check of the status of the GND/PWR/PROT circuit breaker (2XG).
   (1) If the circuit breaker is open:
     (a) If the fault continues:
  • Replace the C/B-GND/PWR/PROT [2XG] .
   (2) If the circuit breaker is closed:
  • Do a check of the Point-Of-Regulation (POR) sense wiring ASM 244101 for an open circuit or a short circuit between:
    . pin A/J of the EPC (3XG) and pin B/15J of the GAPCU
    . pin A/H of the EPC and pin B/14J of the GAPCU
    . pin A/G of the EPC and pin B/13J of the GAPCU.
     (a) If the wiring is not correct:
  • Repair or replace as necessary.
     (b) If the wiring is correct:
  • Do a check of the external power feeders ASM 244101 for an open circuit, a short circuit, or a short to airframe between:
    . pin A of the external power receptacle (20XG) and pin A/K of the EPC (3XG)
    . pin B of the external power receptacle and pin A/L of the EPC
    . pin C of the external power receptacle and pin A/M of the EPC.
       1 If the feeders are not correct:
  • Repair or replace as necessary.
       2 If the feeders are correct:
Subtask 24-41-00-860-059-A ** ON A/C NOT FOR ALL
C. Do this procedure to make sure that the system operates correctly.
   (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 04:26:54 UTC
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