The Korea Electrotechnology Research Institute (KERI) has developed a pioneering ‘eco-friendly insulating gas’ to replace sulfur hexafluoride (SF6), a significant contributor to global warming in electric power equipment, and developed a design technology to make it applicable to ultra-high voltage transmission circuit breakers.

Of course, power devices must be able to conduct electricity well but an ‘insulation’ function to block electricity is also essential to prepare for unexpected accidents and for safety reasons. SF6 gas offers excellent insulation and with far superior arc extinguishing performance than any other gas, which interrupts fault current in the event of a system failure, it has been used in the power equipment field for over 50 years.

The Problem with SF6

However, the global warming potential of SF6 is 23,500 times that of carbon dioxide, and once leaked into the atmosphere, it stays for as long as 3,200 years and has a negative impact on the environment.

In Korea, as SF6 gas accounts for 60% of the total greenhouse gas emissions emitted by KEPCO, research on the development of alternatives is urgently needed to respond to the climate crisis and achieve carbon neutrality.

Challenges in Developing Alternatives

Although much effort is being made around the world to develop an eco-friendly gas that can replace SF6, it has yet to bring remarkable results, as developing a substitute gas for SF6 is more difficult and challenging than developing new drugs.

• Difficulties in developing an alternative gas for SF6: Different regulations on the use of chemicals in each country, and as it is a sensitive chemical substance, litigations may arise due to different interests of nations, it is difficult to be developed by private companies in a short period of time (cost and time required, high possibility of failure), lack of ability to analyze gas materials, etc.

Despite this high possibility of failure, KERI embarked on the research and development with the mission of a national research institute to respond to global carbon emissions regulations and the enormous effects expected with the successful development of SF6 alternative gas.

First, among the gases currently used in industry, substances with a low global warming potential were sorted out, and the electrical and chemical properties of the selected primary candidates were closely analyzed to determine the 2nd round candidates.

Development of K6 Gas

Then, the final candidate materials were selected based on the results of insulation and explosion/ignition control performance tests, and the optimal ratio for application to power devices was derived to develop eco-friendly insulating gas. KERI named this independently developed gas ‘K6.’

• K6: meaning K of KERI + final substances were derived in the 6th times in the 2nd round candidate group

K6 gas is environmentally friendly with a global warming potential of less than 1, and does not contain any serious toxic ingredients. The ‘boiling point’, which is a prerequisite for applying gas to power devices, is also low (–26°C), making the gas applicable in most areas.

Impact and Future Plans

KERI went further to apply K6 gas to ultra-high voltage (145kV) transmission-level circuit breakers and even passed the Interrupting performance test in accordance with the international standards of the International Electrotechnical Commission (IEC). In particular, ultra-high voltage transmission circuit breakers are considered to be the most difficult areas to apply insulating gas.

Based on the results of the test, KERI plans to apply K6 gas to various power devices (breakers, transformers, switches, etc.) from distribution to transmission.

Dr. Yeon-ho Oh, head of Eco-Friendly Power Apparatus Research Center, KERI said, “K6 gas has better performance and is more environmentally friendly than other insulating gas that has been led by advanced overseas companies.” He added, “As Korea has the top-tier position in export in the global power device industry, the development of K6 gas will have a huge impact not only on the environment but also on the economic and industrial front.”

Based on the achievement, it is planned to prepare for commercialization with technology transfer to Korean power apparatus companies. KERI is committed to contributing to strengthening the competitiveness of the domestic power apparatus industry by establishing clear design standards for the wide use of eco-friendly gas through continuous communication with the industry.

KERI is a government-funded research institute under the National Research Council of Science & Technology of the Ministry of Science and ICT. This study was conducted in collaboration with the Korea Research Institute of Chemical Technology, Korea Research Institute of Standards, Korea Institute of Fusion Energy, and Korea Institute of Toxicology