RMU with Eco-Efficient Gas Mixture: Evaluation after 3 years of Field Experience

Abstract

Gas-insulated switchgear (GIS) are key components in medium voltage (MV) distribution networks. SF6 gas is the preferred insulation medium for GIS. However, SF6 has a high global warming potential (GWP) of 22800 and might be targeted for replacement by the EU Commission. Power and automation equipment supplier ABB has developed eco-efficient GIS solutions based on the AirPlusTM gas mixture consisting of dry air and Novec 5110 C5F10O-fluoroketone (C5-FK). For MV secondary distribution applications, the AirPlus gas mixture must have a dew point below -25°C. A three-year field experience program was started in November 2015. Four SafeRing AirPlus ring main units (RMUs) were installed in Liander’s network in Flevoland, Netherlands. Gas samples were collected and analysed several times per year and the units were visually inspected during site visits. Two of the four RMUs were returned to ABB for further inspection at the end of the 3-year period. The results of the gas analysis and measurements confirmed that no significant change has occurred since the units were installed and energized. The outcome of the measurements and observations during and after the three years (2015-2018) of service will be discussed in this paper.