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Article Date: 2nd August 2016

ABB Power Grids - AirPlus Offer an Eco-Efficient Alternative to SF6 Switchgear

SF6 Switchgear - Gas-Insulated Switchgear - Medium-Voltage GIS

ABB Power - AirPlus Molecules

For decades, sulphur hexafluoride (SF6) has been the predominant insulation medium for switchgear due to its technical properties. However, with global warming and climate change becoming worldwide concerns ABB has been active in the development and deployment of alternatives to this greenhouse gas.

SF6 made gas developed in the early 20th century which, due to its excellent properties for electric insulation and arc interruption is used extensively as the dielectric medium in high and medium-voltage switchgear. In addition to enabling safe and reliable operation, it has also made it possible to significantly reduce the size of switchgear installations, and remain as the main insulation medium for years to come.

However, SF6 gas and its lifecycle management requires careful handling and can entail substantial costs, particularly when decommissioning ageing substations. As the demand for electricity rises worldwide, especially in emerging countries, demand for high-voltage switchgear is also rising. That is the main driver in the search for alternative gases to SF6 for reduced environmental impact.

ABB Power - AirPlusA new fluoroketone-based gas mixture
ABB achieved a recent breakthrough with a new alternative to SF6 by commissioning the world’s first high- and medium-voltage gas-insulated switchgear (GIS) bays with a new eco-efficient gas mixture - ‘AirPlus’. This fluoroketone-based gas mixture is a chemical compound developed for switchgear applications in collaboration with 3M. The GIS bays for 24 kV and 170 kV voltage ratings were installed in a pilot substation in Zurich operated by leading Swiss utility Ewz, which was inaugurated in August 2015.

This new AirPlus gas mixture contains:

  • Fluoroketone (C5-PFK), carbon dioxide (CO2) and oxygen (O2) for (high-voltage) GIS
  • Fluoroketone (C5-PFK), nitrogen (N2) and oxygen (O2) for medium-voltage GIS

The fluorinated molecule has a chemical composition that decomposes under ultraviolet light in the lower atmosphere. Therefore the molecule’s atmospheric lifetime is extremely short (less than 15 days versus 3,200 years with SF6) and it decomposes into negligible quantities of CO2 that are not harmful for the environment. Because of this, its Global Warming Potential (GWP) is less than 1, even lower than CO2 (GWP=1). In addition, the fluorinated molecule is practically non-toxic, non- flammable and neither the substance itself nor the effects of decomposition will deplete the ozone layer.

This GWP is almost 100 percent lower than that of SF6 without any compromises on equipment quality and reliability. The new gas mixture is the only one available so far that meets the performance criteria after being type tested according to IEC standards and has a GWP <=1. In addition, as per the lifecycle analysis (LCA) of the product, deployment of high-voltage GIS with these new gas mixture CO2 emissions by up to 50 percent through the lifecycle of the equipment, the other half being attributable to raw materials, manufacturing and thermal losses.

ABB Power - GraphAirPlus range
Building on the success of the trial installation, ABB has now launched the world’s first AirPlus gas-insulated switchgear range.

Bruno Melles, managing director of ABB’s Medium Voltage business, said: "This is a great example of ABB innovating to deliver its ‘Better World’ promise. We use gas mixture as the insulation medium for our switchgear that has a GWP almost 100 percent lower, we retain the quality and reliability and compact footprint that our customers expect from a market leader."

The first two switchgear products with AirPlus will be available in 2016. ZX2 AirPlus is the new primary distribution switchgear available in an IEC rating of up to 36 kV, with 31.5 kA short-circuit and 2,000 A nominal current. SafeRing AirPlus is the new secondary distribution ring main unit (RMU) available in IEC ratings up to 24 kV with 16 kA short-circuit and 630 A nominal current. The good technical performance of AirPlus made it possible to retain the same compact dimensions of ABB’s well established medium-voltage GIS. Both new products are based on proven and widely-accepted existing switchgear designs with the same level of safety and reliability.

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