Fault Message:

GEN1 DELTA CURRENT FAULT

Fault Code:

2421118LPS

Associated CAS:

GEN 1 FAIL
(Advisory)

The Generator Control Unit (GCU) 1 detects between two phases a difference in output current larger than 35A ± 5A.

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

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

A GCU patch cable (GSE REF # 24X-24-02) can be used to swap GCUs 1, 4 and 5 into position 2 or 3 (for troubleshooting only).

The GCU NVMs can only be downloaded at position #2 or #3.

1. Check for CAIMS message related to the ACPC short circuit fault. Clear/troubleshoot the message first if existed.

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

2. Swap GCU 1 with GCU 2 (physically or using the GCU patch cable).
   NOTE: Use PMAT to monitor the fault on GCU.

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

3. Disconnect T1, T2, T3 and G at VFG 1. Perform continuity check (closed circuit = failure) as follows:

   From	To	Result
   G1-T1	Ground
   G1-T2	Ground
   G1-T3	Ground
   G1-G	Ground

   1. If there is continuity, go to step 20.
   2. If there is no continuity, continue with next step

4. Perform wiring check (open circuit = failure) between VFG and ACPC as follows:

   From	To	Result
   G1-T1	ACPC VFG1-T1
   G1-T2	ACPC VFG1-T2
   G1-T3	ACPC VFG1-T3

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

5. Disconnect connector G1P1 on VFG 1. Perform continuity check (open circuit = failure) on VFG 1 as follows:

   From	To	Result
   G1P1-F	G1P1-D
   G1P1-E	G1P1-D
   G1P1-J	G1P1-D

   1. If there is no continuity, go to step 20.
   2. If there is continuity, continue with next step.

6. Perform continuity check (closed circuit = failure) on VFG 1 as follows:

   From	To	Result
   G1P1-F	Ground
   G1P1-E	Ground
   G1P1-J	Ground
   G1P1-D	Ground

   1. If there is continuity, go to step 20.
   2. If there is no continuity, continue with next step.

7. Disconnect GCU1 connector A56P2. Perform continuity check (open circuit = failure) between G1P1 and A56P2 as follows:

   From	To	Result
   G1P1-F	A56P2-41
   G1P1-E	A56P2-42
   G1P1-J	A56P2-50
   G1P1-D	A56P2-40

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

8. Perform wiring check (closed circuit = failure) between G1P1 and ground as follows:

   From	To	Result
   G1P1-F	Ground
   G1P1-E	Ground
   G1P1-J	Ground

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

9. Disconnect ACPC connector A54P6. Perform continuity check (open circuit = failure) between A56P2 and A54P6 as follows:

   From	To	Result
   A56P2-49	A54P6-E
   A56P2-57	A54P6-F
   A56P2-63	A54P6-G
   A56P2-62	A54P6-H

   1. If there is no continuity, repair defective wiring as required and do close out.
   2. If there is continuity, continue with next step.

10. Perform wiring check (closed circuit = failure) between A56P2 and ground as follows:

    From	To	Result
    A56P2-49	Ground
    A56P2-57	Ground
    A56P2-63	Ground

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

11. Perform continuity check (open circuit = failure) between VFG1 and K5 as follows:

    From	To	Result
    G1-T1	K5-A1
    G1-T2	K5-B1
    G1-T3	K5-C1

    1. If there is continuity, go to step 13.
    2. If there is no continuity, continue with next step.

12. Repair wiring (including inside ACPC) between VFG1 and K5 as follows:

    From	To	Result
    G1-T1	K5-A1
    G1-T2	K5-B1
    G1-T3	K5-C1

    1. If wiring checks are not good, repair defective wiring as required and do close out.
    2. If wiring checks are good, continue with next step.
       NOTE: Call Bombardier for decision to repair ACPC wiring or replace ACPC.

13. Perform wiring check (closed circuit = failure) between VFG1 and ground as follows:

    From	To	Result
    G1-T1	Ground
    G1-T2	Ground
    G1-T3	Ground

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

14. On current transducer 1 (LCTA1), disconnect connector PL1. Perform continuity check (open circuit = failure) in ACPC between A54P6 and PL1 as follows:

    From	To	Result
    A54P6-E	PL1-1
    A54P6-F	PL1-2
    A54P6-G	PL1-3
    A54P6-H	PL1-4

    1. If there is no continuity, go to step 21.
    2. If there is continuity, continue with next step.

15. Perform continuity check (open circuit = failure) in ACPC between A54P6 and ground as follows:

    From	To	Result
    A54P6-E	Ground
    A54P6-F	Ground
    A54P6-G	Ground

    1. If there is continuity, go to step 21.
    2. If there is no continuity, continue with next step.

16. Perform continuity check (open circuit = failure) at connector PL1 as follows:

    From	To	Result
    PL1-1	PL1-4
    PL1-2	PL1-4
    PL1-3	PL1-4

    1. If there is no continuity, go to step 18.
    2. If there is continuity, continue with next step.

17. Perform continuity check (short circuit = failure) at connector between JL1 and ground as follows:

    From	To	Result
    JL1-1	Ground
    JL1-2	Ground
    JL1-3	Ground

    1. If there is no continuity, go to step 19.
    2. If there is continuity, continue with next step.

18. Replace LCTA1.

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

19. Replace GLC1 (K5).

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

20. Swap VFG 1 with VFG 2.

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

21. Replace ACPC.
22. Do close out.