Abstract: SF₆ gas density relays are used to monitor gas density changes in SF₆ insulated equipment, whose performances have a direct influence on the safety and reliability of the equipment. Data from fields shows that the temperature compensation performances of SF₆ density relays will become worse in extremely unusual weather conditions, which will lead to greater errors. Therefore, it is necessary for SF₆ gas density relays to be calibrated in those weather conditions. A kind of calibration devices for SF₆ density relays in extremely unusual weather conditions and a set of calibration methods especially applied to North China areas with very low temperature were introduced. Test results suggest that a density relay with dual metal compensation is preferable than a standard cavity compensation relay in an extremely low temperature condition. By the performance calibrations, the action reliability and accuracy of a SF₆ density relay can be ensured, which can prevent some kinds of power grid accidents from happening.

Key words: SF6-gas-insulated equipment, gas density relay, calibration, extremely unusual temperature