Abstract: This paper addresses system faults caused by the standalone “and logic module” in the HCM200 DC control and protection system at converter stations.Referencing fault instances from Jinhua Converter Station, we study and analyze similar faults at the Yinchuan East Converter Station, and discuss potential alarms and protective responses that could be triggered by a module failure, propose the targeted strategies for troubleshooting, hazard prediction, and improving countermeasures for such faults.