Research on the Structural Optimization and Electrical Characteristics of the Arrester in Electric Multiple Units

Due to frequent multiple harmonic overvoltages of the contact wire, the arresters in electric multiple units (EMUs) suffer from accelerated impulse deterioration and serious life threatening. Thus, this article proposes two novel kinds of arresters. One is a compound arrester with parallel gap and zinc oxide (ZnO) varistors (CA-PGZRs), and the other is a compound arrester with parallel gap and linear resistors (CA-PGLRs). Simultaneously, their electrical characteristics are verified by theoretical simulation and experiment. The results demonstrate that: 1) their chopping overvoltage is lower than that of the arrester with the series gap (ASG) under the operating overvoltage (the chopping overvoltage of CA-PGZR, CA-PGLR, and ASG are 75.4, 54.3, and 142.0 kV, respectively); 2) their impulse discharge voltage does not exceed the impulse residual voltage of the arrester body under the standard impulse current; and 3) under the increased power-frequency–voltage or harmonic overvoltage, their stable temperature rises are reduced by more than 50% compared with the gapless arrester (under the harmonic voltage of 47.5 kV and 2050 Hz, the stable temperature rise of CA-PGZR, CA-PGLR, and the gapless arrester is 63.4 °C, 45.4 °C, and 126 °C, respectively). The two proposed arresters in this article show superior protection and tolerance characteristics. They can effectively mitigate the damage caused by harmonic overvoltage to the arrester body and can be used to replace the gapless arrester in EMUs.