Overview of IEC Standards´ recommendations for lightning protection of electrical high-voltage power systems using surge arresters

This contribution deals with the emerging standards of the IEC 60099 series on high-voltage surge arresters. Driven by the demand from UHV systems and by new, experimentally found insights on energy handling capability of metal-oxide (MO) varistors, a new classification concept and new test requirements have been introduced to the latest edition of the main arrester standard - IEC 60099-4, Ed. 3.0 - as well as to the new standard IEC 60099-9, Ed. 1.0, on arresters for HVDC converter stations, both published in 2014. The major alterations in IEC 60099-4, especially those regarding arrester classification, energy handling definitions and test requirements are presented and discussed, and detailed background information is given. Also the main aspects of UHV arrester testing are addressed, as far as they are different from those for “standard” arresters. Another focus of this contribution is on externally gapped line arresters (EGLA), which are covered by a separate test standard, IEC 60099-8. This standard was published in 2011 and is thus not really new, but its application is not yet generally established, though EGLAs constitute an effective solution for improving the overall performance of transmission and distribution lines. Recent findings on energy handling capability are of special interest for this application.