Review of Health and Safety Data on Leading SF6-alternative Gas Mixtures

One of the continuing environmental challenges for the electric power industry results from the use of sulfur hexafluoride (SF6) as a dielectric medium in gas-insulated equipment due to its identification as a potent greenhouse gas. The electric power industry has long searched for alternative insulating gases to replace SF6. In recent years, a fluoroketone and a fluoronitrile have begun to be implemented within gas mixtures in new SF6-free equipment designs. reducing greenhouse gas emissions by 99% or more compared to SF6. This paper reviews the available health and safety data on these alternative gases and risk assessments for their use in electric power applications. Both compounds have been evaluated through a series of toxicological studies and were demonstrated to be low in acute inhalation toxicity, the primary mode of potential exposure in gas insulated system applications. Using these toxicological profiles, risk assessments were conducted on the use of these compounds in gas-insulated equipment taking into account the potential for worker exposure. Under normal operating conditions, as well as with used gas after arcing, the hazards and potential exposures were found to be similar to those observed with SF6, thus, posing similar risks. On this basis, the precautions and personal protective equipment currently employed with new and used SF6 have been recommended for use with these SFs-alternative gas mixtures. As a result, these alternative gases and their mixtures provide a wide margin of safety in these applications.