The ground electrode is an important equipment of HVDC transmission system, providing a path for the ground current and unbalanced current. Due to the limitation of land resources, common ground electrodes have increasingly become the choice for HVDC transmission system. Most of the ground electrodes of China Southern Power Grid Corporation are common ground electrodes. Therefore, this paper takes the common ground electrode of a ±800kV HVDC project as an example, and analyzes that characteristics of circulating current of cable armor in common ground electrode center, which causes cable burnt out. The research results show that the terminal tower of electrode station is located outside the electrode ring, which increases the potential difference between the two ends of the armor layer of feeder cable, and tens of amperes circulating current during the feeder cable. This eventually caused the cable joint to catch fire, damaging the cable.
 

electrode; cable;circulating current; HVDC