ABB has achieved a breakthrough in gas insulated switchgear (GIS) technology by commissioning the world’s first high- and medium-voltage GIS bays with a new eco-efficient gas mixture as an alternative to the widely used greenhouse gas SF₆.
A switchgear combines electrical switches, fuses or circuit breakers to control, protect and isolate electrical equipment in a power network. Switchgear is installed throughout the power value chain from generation through to transmission, distribution and consumption, across voltage levels. High and medium voltage switchgear is generally installed in power transmission and distribution, helping to ensure grid reliability, efficiency and safety.
ABB’s new eco-efficient switchgear uses an SF6 alternative gas mixture as the insulation medium and additionally as switching medium for the high voltage switchgear. The fluoroketone based SF6 alternative gas mixture is a chemical compound developed for switchgear applications in collaboration with 3M. Global warming potential (GWP) of the new gas mixture is almost 100 percent lower than that of SF6, without any compromise on equipment quality and reliability. This can result in lowering CO₂ equivalent emissions of the GIS by half, through the lifecycle of the equipment – the other half being attributable to raw materials, manufacturing and thermal losses.
The 170/24 kV switchgear bays have been supplied to leading Swiss utility ewz for their newly energized 3 x 50 megavolt ampere (MVA) substation in Zurich, Switzerland, which supplies electricity to the northern and one of the most populous part of the city - home to approximately 50,000 inhabitants as well as Zurich’s largest event hall and trade fairgrounds. Low-noise and high efficiency power transformers and substation automation protection and control systems from ABB have also been deployed in the substation.
Located 15 meters underground, the strikingly designed GIS substation replaces an outdoor air-insulated switchgear (AIS) substation built in 1949, freeing up about 70 percent of the space occupied by the old substation for other requirements and enhancing the aesthetics of the cityscape.
For decades, SF6 gas has been used extensively in the electrical industry for dielectric insulation and current interruption due to its physical properties. Pressurized SF₆ gas facilitates the safe and reliable operation of gas-insulated switchgear, making it possible to significantly reduce the size of switchgear installations. However, it is a greenhouse gas and its lifecycle management requires careful handling and can entail substantial costs, particularly when decommissioning aging substations.