Abstract: This paper addresses the frequent "control circuit break" alarms in a 10 kV high-voltage switchgear at a distribution substation during actual operation. By analyzing the system's operational mode and the secondary circuit schematic, it was determined that the abnormal alarms originated from a design defect in the secondary circuit: The closing lockout contact was incorrectly wired into the trip position monitoring circuit, leading to misinterpretation of the system status. Based on identifying the root cause, improvement measures are proposed, including modifying the contact wiring position and optimizing operation and maintenance strategies, it is also recommended to enhance technical training for maintenance personnel and strengthen the review of circuit diagrams to improve system reliability and safety.