A testing procedure for RTV pre-coated glass cap-and-pin and composite insulators sampled from field

This paper describes a new testing procedure developed by TERNA (the Italian TSO) for RTV insulators and composite insulators sampled from field. The procedure is based on proper flashover voltage tests, followed by hydrophobicity-recovery tests, and is unique for both RTV and composite insulators. The paper also describes the statistical processing results for a few insulators removed from TERNA's HV and EHV overhead lines after some years' service and tested in an external research laboratory following the proposed procedure.