Wet tests under AC voltage and switching impulses procedure and significant parameters

The lack of reproducibility of wet tests, especially under AC voltage, has been a critical problem for acceptance tests or sampling tests. For this reason a task force was established to improve the wet-test procedure. The test program is described. The role played by the precipitation distribution along the insulator is demonstrated, and consequences for rain intensity measurements and requirements are drawn with respect to the IEC Publication 60 revision. Data on the dielectric strength of post insulators under switching impulses are given for design purposes