Maintenance of Sulphur Hexafluoride Gas

Sulphur hexafluoride (SF6) gas is an arc quenching and cooling medium used in medium and high voltage electrical equipment as an electrical insulator. Under the Kyoto Protocol, SF6 has been classified as a greenhouse gas and restrictions are in place to limit the amount allowed to be released into the atmosphere.

Both manufacturers and the users of their equipment are responsible for the reduction in SF6 gas emissions. Organisations such as the International Electrochemical Commission (IEC) and the International Council on Large Electric Systems (CIGRE) provide guidance and regulatory information with regards to the handling of such a gas when it comes to maintenance.

When partial arcing or a failure occurs within electrical equipment, this can cause the creation of decomposition products such as sulphur dioxide and hydrogen fluoride. Analysis of SF6 gas is recommended as part of a regular condition maintenance schedule, this ensures that equipment and personnel are properly protected. Early identification of elevated decomposition products will help to eliminate power outages and failures, alongside unnecessary inspections.

In order to ensure that no emissions occur throughout the testing process, Cambridge Sensotec (UK) designed the Rapidox SF6 6100 Pump Back gas analyser. The instrument draws a sample of SF6 gas from the electrical equipment and analyses it in accordance with current IEC and CIGRE test configurations. It then pumps it back either automatically or manually, into the electrical equipment at pressure. Alternatively, the analyser can store the gas internally for proper disposal at a later time.