Fault testing of gapless zinc oxide transmission line arresters under simulated field conditions

Gapless zinc oxide (ZnO) transmission line arresters were fault tested under simulated field service conditions to address important reliability issues associated with their application. Specific reliability issues addressed were: (1) failure mode or pressure relief capabilities; (2) the ability of the arrester fault isolation device to isolate a faulted arrester from the system while simulating a high speed line reclosing operation; and (3) verification that the evolving fault is restricted to the faulted phase only and does not involve adjacent unfaulted phases. An important and unique aspect of this test was to demonstrate how the complete assembly, made up of an actual 100 kV tower structure, arrester and associated elements, would perform by documenting results for each of the three reliability issues noted. Test results address important user application issues impacting system reliability and suggest potential focus areas for future standards development work