The external gap arrester FHY5C-10 is an overvoltage protector, which is mainly used to protect various electrical equipment in the power system, railway electrification system and communication system, such as transformers, switches, capacitor banks, wave arresters, transformers, generators, power cables, etc., from atmospheric overvoltage, operating overvoltage, power frequency transient overvoltage and other damages. It is the insulation coordination of the power system