Thyristor Valve Gapless Arrester Element Lifetime Performance and Thermal Stability

For the purpose of developing thyristor valve gapless arrester, a ZnO element was developed and examination was conducted on such characteristics of gapless arrester as life characteristic, thermal runaway characteristic and surge withstand capability, these being essential to rational design of thyristor valve gapless arrester. Especially for evaluating the life characteristic and thermal runaway, a small-scale 3- phase bridge thyristor converter was manufactured to provide the same stress as in the actual system. Based on the result of experiment using the 3-phase bridge thyristor converter, a d.c. 125kV thyristor valve gapless arrester capable of lowering the protective level was developed. The gapless arrester is currently undergoing field testing in the actual system.