Background

If the Aperture Cover drives fault the GIS will not allow the M1 Cover to open and will try to force the Aperture Cover to close. Unfortunately, occasion the Aperture Cover drives will fault at the end of their opening motion with a standstill fault.

To get around this we need to open the aperture cover and reset the drives. However, the logic will close the light path if this happens, which will lead to an aperture cover timeout fault. So, we temporarily force the ready bit on. This will give us time to reset the drives. Then we can disable the bypass and continue normally.

Before bypassing

1. Ensure Aperture Cover is closed.

2. Reset GIS using front panel button.

3. Reset GIS faults using engineering screen on HMI.

4. Verify that Aperture Cover is not forced closed by the GIS.

Bypass Procedure

1. Toggle ApCover_Ready_Bypass in the EMCS PLC on. (Rung 31 of program EMCS_to_LIC in the Main Task)

   

2. Open Aperture Cover fully.

3. Reset Aperture Cover Drives (if faulted).

4. Verify ApertureCover_Drives_RTS is on.

5. Toggle ApCover_Ready_Bypass in the EMCS PLC off.

6. Verify Comm_EMCS_to_LIC.DATA[17].3 remains on.

7. Open M1 cover normally.

8. Observe.

9. Profit.