Sulphur hexafluoride (SF6) is an excellent dielectric gas for high voltage applications. It is chemically inert, gaseous even at low temperature, non-flammable, non-toxic, non-corrosive. Its combined chemical, thermal and electrical properties allow many advantages to be achieved.
Applications for SF6 include gas insulated transmission lines and gas insulated power distribution substations. The combined electrical, physical, chemical and thermal properties offer many advantages when used in power switchgear such as circuit breakers and Power Voltage transformers as quenching and insulating medium respectively because of the following outstanding properties:
- High dielectric strength
- Unique arc-quenching ability
- Excellent thermal stability
- Good thermal conductivity
SF6 is a reliable gas and ensures the reliability of supply in electrical systems. It is neither toxic nor flammable and does not have any carcinogenic, mutagenic or reprotoxic (CMR) characteristics. This provides the highest level of safety for the operator, and the gas remains in a closed circuit, even after the end of the system’s life. On the other hand there is a high global warming potential or GWP of SF6 of 22,800 which contributes to global warming.