Arrester Technology Today: Lessons Learned Developments to Watch

摘要

Gapless Metal-Oxide (MO) arresters came to the market in 1975. The first test standards on these novel devices were published around 1990. Gapless MO arresters are thus comparatively young and modern devices with an only short history, but have nevertheless undergone a rapid development during the past three decades. As an example, MO arresters were among the first apparatus in electrical power systems with polymeric insulation. Impressing progress has been achieved in the permanent improvement of the MO resistor performance, making arresters belonging to the most reliable components in the electrical power system. Energy handling capability and potential electrical degradation has been a concern from the beginning, as due to the permanent connection to the line, a gapless MO arrester can theoretically suffer a thermal runaway after excessive energy input and/or due to deterioration of its nonlinear voltage-current-characteristic. New arrester applications became possible, such as UHV arresters, HVDC arresters, line arresters with and without series gap, huge arrester banks in FACTS and, as a most recent development, as energy absorbers in HVDC circuit breakers. But modern, unconventional applications required approaches in specifying and verifying energy handling capability other than just by line discharges as it was the case in the beginning. Supported by Cigre work, the test standards have permanently been improved in order to cover all aspects of today's arrester applications, though still work has to be done on this way. Anyway, more than for other apparatus the test standards of IEC and IEEE are being harmonized. As one of the most exciting actual developments in engineering, simulation tools have become so powerful that it is possible to optimize EHV and UHV arrester designs with respect to their external grading systems and their thermal stability limits by nonlinear fully coupled electro-thermal simulations. This has opened the door for designing UHV arresters with considerably reduced need for full size testing in the laboratory, which is increasingly difficult in these voltage levels. This contribution addresses some of the challenges and findings during the development of the gapless MO surge arresters, with the focus on research performed at Technische Universitat Darmstadt.