DIN IEC/TS 60815-4:2017-10

This Technical Specification is applicable to the selection of insulators for d.c. systems, and the determination of their relevant dimensions, to be used in high-voltage systems with respect to pollution. It is applicable to: - glass and ceramic insulators; - glass and ceramic insulators with a coating of material with hydrophobic transfer (HTM) or other coating to improve performance in the presence of pollution; - composite and hybrid insulators with a polymer housing; - composite and hybrid insulators with an HTM housing. This part of IEC 60815 gives specific guidelines and principles to arrive at an informed judgment on the probable behaviour of a given insulator in certain pollution environments. The structure and approach of this part of IEC 60815 are similar to those explained in Part 1, but adapted for the specific issues encountered with polluted HV d.c. insulation. The aim of this Technical Specification is to give the user simplified means to: - Identify issues specific to d.c. applications that can affect the choice and design process; - Determine the equivalent d.c. Site Pollution Severity (SPS) from measurements, correcting for electrostatic effects, diameter, pollution distribution and composition; - Determine the reference USCD for different candidate insulating solutions, taking into account materials, dimensions and risk factors; - Evaluate the suitability of different insulator profiles; - Discuss the appropriate methods to verify the performance of the selected insulators, if required; This simplified process is intended to be used when comparable operational experience from existing d.c. system is incomplete or not available. The simplified design approach might result in a solution that exceeds the physical constraints of the project. More refined approaches for such cases, such as using a statistical approach, are given in the CIGRE d.c. guidelines. In extreme cases, for exceptionally severe site conditions for example, alternative solutions such as changing the line route, relocation of converter stations or using an indoor d.c. yard may need to be considered. The responsible committee is DKE/K 451 "Isolatoren" ("Insulators") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.