The insulation, thermal conductivity and switching performance have now been validated. Current interruption capability also shows positive progress, and g3 is safe for operators. Therefore, g3 is suitable for developing a new generation of clean equipment from 72 kV up to ultra-high voltages with extremely low global warming potential.
* g3: trademark application owned by ALSTOM Grid SAS
* 3M and Novec are trademarks of the 3M Company
Next steps
Philippe Ponchon, Grid Solutions VP Marketing and AIS Marketing Director, offers a roadmap for its ground-breaking SF6 replacement.
“Our objective of replacing SF6 in our high voltage equipment stems from our customers’ concern for the environment, as well as present or future pressure from the authorities. The breakthrough we have made is to engineer and test a family of gas mixtures for high voltage switchgear applications. We call it g3. It uses a molecule, developed by 3M in cooperation with GE Grid Solutions and according to Grid Solutions' specifications and guidance, which we have combined with CO2.
“We have already started the development of new products for both GIS and AIS arrangements. In a not too distant future, i.e. from March 2015 we will announce the first specific g3 product.
“Retrofit – to replace SF6 with g3, while adapting some components – is also of major interest for some customers who want to reduce the environmental footprint of their assets as fast as possible. Even if it is only possible in specific cases, we are currently assessing pilot applications with precursor customers.
“The technical foundations are laid; opening the door to the development of new ranges of high voltage equipment comparable to SF6 in terms of performance and footprint, but much more environmentally friendly. It is, from my point of view, the beginning of a major change similar to the move from oil or compressed air to SF6 in the early ’70s. The speed of the move will depend on many parameters – economical, technical and societal.
“On the technical side, in the insulating domain this will enable fast development for all voltages from 72 kV to ultra-high voltages. Circuit breakers are a more complex domain. We have tested some prototypes, with satisfying results. But we are aiming at solutions for all types of circuit breaker on the full range of voltages. This implies modifications to a number of components and exhaustive testing, which will take more time.
“The key parameter will now be how far customers are ready to move to solutions with a global warming potential reduced by up to 98 % and how strong will be the regulatory incentives to protect the planet against climate change!”
Read more: Developing a new gas
John G. Owens, Lead Research Specialist at 3M, talks of the cooperation with Grid Solutions to find an SF6 alternative.
Think Grid: GE Grid Solutions came to you with its specifications. What led you to this particular molecule?
John Owens: 3M’s long history in researching fluorinated materials provided insight into the structure of materials needed to meet GE’s specifications. The unique combination of performance, safety and environmental properties drove our research in new directions. A large number of compounds were evaluated for this application. An understanding of the types of material that did not work was as helpful as those that did work, by directing the synthesis towards materials that showed greater promise.
TG: How is this molecule different from existing ones?
JO: This is the first material to combine all the required properties into one compound. All rejected candidates displayed a serious deficiency in one category or another. An improvement in one property often led to deleterious effects in a different property. This molecule’s structure allowed for the right combination of properties with no significant sacrifice in one of them.
TG: Which other application domains do you see for this molecule?
JO: This material was developed specifically as a dielectric medium. At present, it is best utilised to replace high global warming potential materials such as SF6.