Analysis and Evaluation about characteristic deterioration of Porcelain-housed Surge Arrester with Long service life for 500kV Substation

At present, there have been cases of old arresters exploding under overvoltage in the power systems, and it is urgent to investigate the performance degradation of the arresters which have serviced long time. This paper takes the two-phase arresters A and C as the research object which serviced 22 years on the line side of Puti Station, and sets a arrester with same type that have been serviced for 3 years as the control group, and compares the electrical performance of the new and old arresters horizontally through the test method. Comparing the data of the A and C two-phase arresters in this test with the initial test data and the data during the maintenance test in 2017, the performance degradation of the arresters were analyzed. Disassemble the A and C two-phase arresters to verify the performance degradation and energy tolerance of the resistors which are the core element of the arresters. The test found that the electrical performance of the 22-year-old arrester has shown an obvious aging trend, but the performance of the resistors are still good, meet the standard requirements, and the resistors can be used for a long time according to the Arrhenius' law. The aging performance of the arrester is the result of the combined effect of multiple factors such as service time, the frequency of overvoltage resistance, sealing performance, etc. The aging of sealing performance is the main reason for shortening the life of the arrester. If considering the sealing performance of the arrester is not deteriorated, the porcelain-housed arrester for 500kV power station can meet the total safe operation time of 30 years required by the State Grid's bidding requirements. In the routine operation and maintenance test of the substation, attention should be paid to the changes of parameters such as the reference voltage and leakage current of the arrester. When the DC reference voltage drops by more than 4% and the leakage current exceeds 40μA, it means that the operation of the arrester has a potential safety hazard, and it will be struck by a large overvoltage again. The risk of breakdown and damage is extremely high. Consider replacing the arrester for safety reasons.