Electricity Today T&D Magazine

Insulators installed on HVDC lines have to sustain very unique and specific stress conditions associated with the unidirectional electrical field and current flow that are generating ionic migration, thermal runaway, pollution accumulation and corrosion of metal fittings.

To achieve an optimum performance in DC and to cope with these 4 specific Direct Current constraints, Sediver pioneered, as early as the mid 1980’s, an exclusive DC insulator that combines:

·       a high resistivity toughened glass (HRTG) chemical composition able to block the ion flow

·       an optimized insulator design with an increased leakage distance to enhance the pollution performance and a protection of the metal fittings against electrolytic corrosion

·       a special manufacturing process that produces a very high purity of glass, which makes it less sensitive to ionic accumulation

This development has largely contributed to establishing a high-performance benchmark in the industry, including specific criteria later on introduced in IEC 61325 which is still the only international standard describing HVDC performance requirements.