Eco-efficient alternatives to SF6: Continuing the AirPlus success story
ABB's AirPlus technology takes center stage at CIRED 2019
At CIRED 2019, the world’s most important conference for medium-voltage technologies in distribution grids, ABB continues the success story of its eco-efficient insulation gases.
ABB’s AirPlus™ technology is a revolutionary technology from ABB, and an alternative to sulfur hexafluoride (SF6) gas. Four years ago, at CIRED 2015 in Lyon, France, ABB announced the world’s first eco-efficient AirPlus switchgear at the Oerlikon substation of Swiss utility ewz. Two years later at CIRED 2017 in Glasgow, ABB presented two papers on AirPlus and had the first two products launched to market.
This year CIRED is held in Madrid, Spain and ABB has three scientific papers on the topic. At the conference ABB presents a new load break switch, adds another switchgear to the AirPlus portfolio resulting from fruitful collaboration, and proves the long-term reliability of AirPlus switchgear. Below a short introduction to the papers is given.
New load break switch for climate-friendly SF6-alternatives
When designing gas-insulated switchgear (GIS) with SF6 alternatives, one important task is to compensate the lower insulation performance – to ensure no flashovers occur during operation and dielectric tests. But SF6 can also serve as switching medium, today frequently applied in ring main units (RMUs). Up to now facing the ‘switching challenge’ has been circumvented by using vacuum interrupters, where switching happens outside the insulation gas.
The use of vacuum interrupters facilitated the first generation of eco-efficient RMUs, compensating the poorer arc-quenching performance of climate-friendly insulation gases compared to SF6. However, vacuum technology comes with downsides compared to load break switch (LBS) designs with puffer-interrupters and knife-type switches used in SF6 today: Requiring an additional disconnector/earthing switch, vacuum interrupters are more costly, bigger in size and change the operation scheme. With puffer-interrupters optimized for the use with eco-efficient SF6-alternative gases, the downsides of vacuum switching can be overcome.
The paper demonstrates that ABB has successfully optimized puffer-type switches to work with climate-friendly gases like dry air and AirPlus, paving the way for the next generation of eco-efficient RMUs. A prototype on ABB’s exhibition stand at CIRED showcases a possible RMU design using the new LBS.
AirPlus innovating in air-insulated switchgear for ENEL
Although gas-insulated switchgear (GIS) is the obvious application for climate-friendly SF6 alternative gases, it is not the only one. SF6 can also be used in air-insulated switchgear (AIS), especially for components like circuit-breakers or switch-disconnectors, to be more precise.
Italian Distribution system operator (DSO) ENEL has been using AIS switchgear with SF6 equipment in their distribution networks. The switchgear according to their DY800 specification mainly uses the ambient air as insulation medium, but also has an SF6 containment for a combined vacuum-interrupter and disconnector-earthing switch.
To meet their needs of a climate-friendly alternative to SF6, ENEL joined forces with ABB to develop switchgear based on their DY800 specification using the AirPlus technology. The joint paper from ENEL and ABB presents the development steps and successful application in pilot installations of this fruitful collaboration.
Successful 3-year field test of SafeRing AirPlus
When introducing a new technology, lack of long-term experience can cause reluctance among potential users. This holds true especially for industries where products are expected to work reliably for 30 years or more, as is the case for gas-insulated switchgear. Field studies under real-life operating conditions are crucial to overcome those reservations.
Four SafeRing AirPlus ring main units (RMUs) have been in service in Liander’s networks of a wind farm in the Netherlands since 2015. Regular gas probes have been collected, and two RMUs were returned to ABB for testing and inspection. The paper demonstrates that the RMUs with eco-efficient AirPlus insulation gas have worked reliably over the 3-year test period. The exposure to changing load and climate conditions has not affected the gas quality, and all materials have proven their suitability for the use with the climate-friendly AirPlus insulation gas.