Pollution exposure under icing and snow is a highly relevant environmental factor for dielectric reliability of post insulators at air-insulated substations, especially in the case of HVDC. This exposure also affects key equipment that relies on post insulators, including disconnectors and bus-bar supports. Generally, these kinds of insulators are in porcelain and more recently also in composite materials. A hybrid solution is also on the market. Post insulators and selection of their relevant dimensioning is typically supported by international standards such as IEC 60273, 60507 under the required service conditions. These standards have been well consolidated and are useful for taking into account the main parameters such as electrical as well as mechanical exposure to pollution and ambient conditions during service. Unfortunately, published reports on performance of post insulators under icing are still limited.
Attend the 2017 INMR WORLD CONGRESS in Barcelona-Sitges this November to hear a paper by Eros Stella of GE Power in Italy that, among other things, analyzes the effect of icing on post insulators. His Paper will compare results of the same kinds of test performed on different post insulators, showing main differences and the parameters that most affect them. These tests provide useful information on proper design of post insulators subject to icing. Based on test results and published information, main design parameters are proposed for post insulators with ice accretions in the range of 0 to 42 mm diameter.