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.
The specific conditions of DC applications require that the insulator be designed to reduce the risk of excessive dust accumulation resulting from unidirectional electric fields. In DC application Sediver recommends the selection of glass profiles with self-cleaning properties of reduced pollution build-up.
FOG types profile
In heavy polluted areas
In desert areas
In heavily polluted areas with solid pollution
From 70 kN up to 840 kN
Sediver extensive HVDC worldwide experience
- 50+ years of experience in HVDC applications
- More than 9,5 million Sediver insulators have been installed all around the world on the most prestigious HVDC transmission lines up to 800 kV