Introduction   During the earth return and metallic return mode conversion of China's HVDC transmission projects in operation, several MRTB (metallic return transfer breaker) or ERTB (earth return transfer breaker) oscillation platform arrester damage have occurred, leading to conversion failure. Therefore, it is necessary to study several modification plans of DC transfer breaker arrester.

  Method   Regarding the characteristics of high energy absorption, long current flow time and high ratio of residual voltage to reference voltage of the DC transfer switch arrester, the calculation results of the arrester's absorbed energy, flow time and overvoltage were proposed to judge whether the two modification plans of increasing the number of arrester columns and increasing the number of valves in series per column could improve the operation environment of the arrester, and the impact on the insulation level of other equipment and the arrangement of equipment were also analyzed in this paper.

  Result   Increasing the number of arrester columns has no obvious effect on improving the operation characteristics of the arrester. Increasing the number of valves in series per column can reduce the current flow time of the arrester but will increase the insulation level of the circuit breaker and the capacitor of the oscillation circuit.

  Conclusion   It is not recommended to increase the number of columns or the number of valves in series per column of the HVDC transfer switch arrester in the existing converter station. It can be transferred at a lower power level to reduce the stress of the arrester. If the energy margin of the arrester is sufficient, measures can be taken to remove the faulty unit and continue operation in the event that the arrester fails due to valve defects.