The behaviour of insulator strings under dry and wet conditions

The paper deals with the estimation or calculation of the flashover voltage for different insulator configurations under dry or wet conditions. The main parameter influencing the flashover voltage is the arcing distance. The others parameters influencing the flashover voltage are mainly the material of insulator (composite, glass, porcelain), configuration of insulator string (suspension, tension, ”V” string or the others special configurations), IEC standard setup (bar 300 mm, wire 1000 mm) and the parallel arrangement of insulators (single, double or triple). Especially the measured values of switching impulse voltage test are very interesting and the behavior of insulators under these tests are still not explained satisfactory. The flashover voltage estimation for insulator strings should explain the behavior of insulators during testing and help in the designing of insulators.