Study on fog flashover performance and fog-water conductivity correction coefficient for polluted insulators

The pollution flashover performance of insulators is generally tested by the steam fog method. However, environmental temperature in tests differs greatly, so the dispensability of test results is high. Moreover, the influence of fog-water conductivity has not been taken into account. Compared with the steam fog method, the cold-fog method simulating natural fog is more consistent with the actual operating conditions of transmission line insulators. This deals with the influence of salt deposit density (SDD) and fog-water conductivity on pollution flashover performance. The influence of the two factors is determined by analysing the results of laboratory experiments where polluted insulators were tested by using the cold-fog method. The results show that the 50% AC pollution flashover voltage ( U 50 ) decreases as SDD and fog-water conductivity increase. The correction coefficient ( K ) indicating the influence of fog-water conductivity on U 50 can be expressed as an exponential function, where the factors are 0.0476, 0.0587 and 0.0567 for samples A, B and C, respectively.