A Study On The Metal Oxide Varistors(MOV) For 500kV Series Capacitors And Thyristor Controlled Series Capacitors

In order to improve the power transmitting capability of transmission lines, two sets of series compensations have been installed in our country recently with equipments directly imported from abroad.Metal Oxide Varistors (MOV) are highly nonlinear components used for overvoltage protection of both EHV SCs and TCSCs. Those MOVs have to be in parallel installation in platforms and even in parallel structure within each MOV unit. But studies have never been done in China in the past few years. In order for the SC and TCSC equipments to be homemade, deep researches have been made firstly to MOVs in this paper.Special attention is devoted to the most difficult problem concerning the uniformly sharing of fault current among all shunt columns in a MOV in this paper. A series of research tests to ZnO elements have been made in order to solve this problem, and some very useful properties have been found. The paper finally ends with a configuration design for the powerful MOV.