Fault Message:

GEN1 OVERCURRENT FAULT

Fault Code:

2421115LPS

Associated CAS:

GEN 1 FAIL
(Advisory)

Generator Control Unit (GCU) 1 has reported an over current on one phase of the Generator (GEN) 1.

• Generator Control Unit (GCU) 1 (A56)
• Variable Frequency Generator (VFG) 1 (G1)
• AC Power Center (ACPC) (A54)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Over current detection specification:

• The output current on one phase of the GEN#1 is more than 185 Amps

CAUTION: Due to the nature of this CAIMS message, wiring checks should be performed prior to swapping any LRUs in order to prevent damage to LRUs or aircraft.

1. Perform a visual inspection for arcing evidences of ACPC primary section. Focus on K5, GEN#1 and GEN#1 feeder cables.

   1. If arcing evidence is found, repair/replace damaged components.
   2. If fault remains, continue with next step.

2. Perform operation test of GEN #1.

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

3. Swap the GCU #1 with GCU #2.

   1. If system checks are good, replace GCU#1 and do close out.
   2. If fault remains, continue with next step.

4. Check for short circuit to GND at T1, T2 and T3 on GEN#1.

   1. If short circuit is found, go to step 13.
   2. If fault remains, continue with next step.

NOTE: Disconnect the power feeder cables on studs T1, T2, T3 and the ground cable (G) for short circuit test.

5. Perform wiring checks between ACPC,GCU#1 and GEN#1.

   1. If wiring checks are not good, repair the defective wiring and do close out.
   2. If wiring checks are good, continue with next step.

6. Check for short circuit to GND between GCU#1 and ACPC wiring.

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

NOTE: Disconnect A56P2 and A54P6 for short circuit test.

7. Check for short circuit to GND between GEN#1 and ACPC wiring.

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

NOTE: Disconnect power feeder cables on studs T1, T2 and T3 on ACPC and GEN#1.

8. Check for short circuit to GND between GEN#1 and GCU#1 wiring.

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

NOTE: Disconnect A56P2 and G1P1 for short circuit test.

9. Check for consistency of resistance for GEN#1 coils by measuring all phases G1P1 pins F, E, J to P (COM).

   1. If resistance is out of range, go to 13.
   2. If resistance is within, continue with next step.

10. Check for consistency of resistance for ACPC coils by measuring all phases A54P6 pins F, E, G to H (COM).

    1. If resistance is out of range, go to 12.
    2. If resistance is within, continue with next step.

11. Replace K5.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

12. Replace ACPC.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

13. Replace GEN#1.
14. Do close out.