RTV pre-coated cap-and-pin toughened glass insulators - a wide experience in the Italian overhead transmission system

This paper describes TERNA's experience over more than one decade of service of RTV coated toughened glass cap-and-pin insulators in AC lines. The installation of almost one million units and laboratory tests for the continuous monitoring of samples taken from the field have enabled promising estimates of the coating end-of-life and have increased remarkably the confidence about their reliability. In addition, trial installations of pre-coated insulators on DC lines have provided interesting results for the use of RTV coated insulators in HVDC overhead lines. Some considerations on the application of RTV half-coated cap-and-pin toughened glass insulators are also made.