WG.B3.45. TB 802: Applications of Non-SF6 Gases or Mixtures in Medium and High Voltage Gas Insulated Switchgear

Despite its remarkable insulating and arc quenching characteristics, SF6 is a significant contributor to greenhouse gases and the industry is trying to minimise and better manage the use of this gas.  This article describes key aspects of the TB which covers the available non-SF6 gases and the requirements for their safe, reliable and sustainable application in gas-insulated switchgear. 

In recognition of the significant work related to the use of non-SF6 gases, Working Group B3.45 has now produced Technical Brochure (TB) 802. This Brochure describes the need for adaptations or new requirements for the safe, reliable and sustainable application of non-SF6 gases and gas mixtures in gas-insulated switchgear. It also describes the properties and availability of the non-SF6 gases and gas-mixtures, which have been investigated and applied to gas-insulated switchgear.  The Australian Panel Convenor for B3 is Crina Costan.

The use of non-SF6 gases is receiving significant attention.  Several pilot projects are underway and experiences and references are available.  It is likely that its use will continue to increase and this TB is a timely source of detailed information for users.

Topics covered by the TB are: 

• Quality and purity requirements, including typical measurement standards and techniques.
• Aging aspects and testing methods, recognising the expected long lifetimes for switchgear of 30 years or more, the impacts of varying operational requirements and the desire for minimal maintenance operation.
• Gas handling and filling accuracy, including gas transfer, quality measurements, filling accuracy, gas treatment and cleaning and the gas filling procedures.
• Tightness requirements, where the leakage rates relate to the environmental, health and safety impacts as well as ongoing performance requirements.
• Minimum functional gas composition and its relation to the minimum functional pressure for insulation and/or switching.
• Health, Safety and Environmental aspects such as toxicology, gas handling, large-scale leaks and external fires.
• Maintenance and life cycle aspects including end-of-life considerations and gas reuse concepts for high voltage gas insulated switchgear. The various maintenance strategies will need to be tailored to suit the individual gas types used.  Medium voltage switchgear is free of maintenance over its lifetime.

The Brochure also covers ongoing development of alternatives for SF6 and application restrictions and issues arising from the pilot projects that are applying alternative gases. It summarises today’s state of the art, and collects and describes principles that apply to a range of gases and gas mixtures. Those principles can be used to characterise any kind of alternative gases to SF6, which might come up in the future.

 The TB is available via e-cigre free to members and €270 to non-members.