Abstract: Taking the ±800kV Guanggu converter station with layered access at the receiving end as an example, the structural principle of the DC voltage divider, the voltage balance control strategy of the layered access valve group at the receiving end, and the logic of the valve group overvoltage protection action were analyzed. Combined with the secondary voltage measurement fault of the DC voltage divider between the valve groups, which caused the valve group to lock, the analysis of the valve group overvoltage protection action and on-site fault inspection verification were carried out. The conclusion was drawn that the secondary voltage measurement fault was caused by the cable breakage of the low-voltage bridge arm voltage signal output circuit, and the cable breakage was caused by multiple factor coupling. The fault handling was accurately completed. Corresponding improvement measures have been proposed for the multiple factors that caused the cable to break, providing theoretical and practical references for the design and configuration of DC voltage dividers in operation and subsequent DC transmission.