With analysis of the insulation-coordination and configuration of line arresters with series gap in 220 kV transmission lines,the technical parameters of line arresters,the design principle and configuration of series gaps were determined.

Its series gap and four branches structure make use of reducing its applied voltage ratio, prolonging its life span, improving protect performance of the phase to phase.

Several key problems in the application of line surge ZnO arresters were discussed in this paper, including the selection and requirements for line surge arresters, the design of polymeric housing and active part of arrester, the design of the series gaps, and their installing sites.

Aiming at the phenomenen of Spark Gap System Self-Triggering during the artificial single-phase grounding test on the MOV of Hechi fixed series compensation(FSC) device,this paper analyzes the cause of the phenomenen based on the functional principles of the spark gap system.