We have Simotion D425 with C120 installed. 

When the F30027 "Enable Signal FBFE (hex) Status 9 " fault occur,

how to identify the faulty unit is Active Line Module (ALM) or Active Interface Module (AIM) ?

(1) From Enable Signal FBFE (hex.), that gives:-

          Bit 0: Power Supply of the IGBT gating shut down, and

          Bit 10: Overcurrent Detected

          which points to ALM, as AIM has no IGBT.

(2) From Status 9, that gives:-

          Status 9: Pre-charging, DC link Voltage end of pre-charging still not detected.

(3) What to measure the voltage of AIM output / ALM input, but fault occur as soon as the AIM contactor close, that put it open again before any measurement can be taken.

The ALM was replaced, and the fault still exist.

By the end, AIM found to be defective, and the ALM was good. Both spare parts cost a lot.

So, the next time F30027 occur, how to identify the faulty unit ? ALM or AIM just from reading the fault message?

What else ( any procedures ) can be done to help for the diagnostic?   

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Split from 0.F30027 error..