ABB takes AirPlus technology to the next level
AirPlus as switching gas – for a future cost reduction
On CIRED 2017, the world’s most important conference for Medium-Voltage technologies in the distribution grid, ABB presents great progress on its eco-efficient AirPlus insulation gas to the scientific audience.
After launching the first two medium-voltage (MV) gas-insulated switchgear (GIS) products with AirPlus in 2016, ABB is now taking the AirPlus technology to the next level. Three CIRED papers underline the suitability of this breakthrough technology for MV GIS applications. Besides highlighting a SafeRing AirPlus pilot with already 1.5 years in operation, two papers address the important topics of environmental and safety aspects as well as the suitability of AirPlus as switching medium.
AirPlus as switching gas – for a future cost reduction
In the MV AirPlus products available today, the new gas mixture is solely used for electrical insulation and heat dissipation inside the gas compartments. For current switching however, these switchgear count on the vacuum technology. An alternative solution is presented that allows switching inside the AirPlus gas.
Although vacuum interrupters are a proven and reliable switching technology, they require a more complex panel design and come with a higher cost – especially compared to the load switches used in SF6 ring main units (RMU) today. These RMUs play an important role in the European distribution grids, as they provide energy for residential areas, commercial buildings or even smaller industries.
The paper shows that AirPlus has proven to be a reliable switching medium in a new load switch design based on the puffer principle. In addition to the successful switching tests according to latest IEC standards, the paper highlights the stability of the gas and outlines the very low generation of byproducts in only trace amounts. So even after 100 switching operations of full load currents, AirPlus was found to be in a comparable, non-toxic state, as the new gas .
Although the new switch is still under development and not yet available in a standard product, the results are very promising for the future of the AirPlus technology. This major breakthrough paves the way for wider application as an ABB’s eco-efficient SF6 alternative, and will allow premium price reductions of AirPlus GIS over traditional SF6 switchgear.
Health and safety aspects of AirPlus insulated GIS
Although ABB’s modern MV GIS do not usually require any gas handling on site over the switchgear’s lifetime, a defect or unexpected event can never be entirely excluded. The CIRED paper addresses the health and safety risks related to AirPlus GIS in regular operation as well as defect and the worst-case scenario of an internal arc fault. As a conclusion, the risks are on a similar or even lower level compared to GIS with SF6, which has been used widely for decades in many parts of the world.
During regular operation of modern GIS switchgear, the gas leakage rates are at a very low level. The paper shows that neither the AirPlus components nor their decomposition products cause any harm to personnel, as all concentrations are far below the permitted operational exposure levels. Also in case of defects with a major gas leakage, it is still safe to enter the switchgear room.
An internal arc failure can produce toxic gases, no matter whether the equipment is insulated with air, SF6 or AirPlus. The concentrations of harmful decomposition products for AirPlus are moderately higher than for air, but significantly lower than for SF6.
The paper concludes that GIS with AirPlus is not only a step forward in terms of global warming, but also safe during operation and defect conditions. In the event of failures, the environmental and safety impact is clearly lower than for SF6.