Early SF6 gas leakage detection through a novel comparison algorithm based on pressure only

Journal article, 2023

SF6 gas is widely used in high voltage switchgear thanks to its excellent electrical properties. Unfortunately it is also the most potent greenhouse gas known today, where 1 kg of SF6 is equivalent to approximately 25 tons of CO2. Therefore it is important to monitor equipment containing SF6 to find and repair any leakage as early as possible. This paper discusses both practical challenges and provides a novel algorithm, that can be used for automatic and early SF6 gas leakage detection for circuit breakers. The work is based on laboratory and field tests in three substations in the south of Sweden. The tests has been carried out with two different types of digital SF6 gas sensors: a density sensor and a pressure sensor. The core of the early SF6 gas leakage detection algorithm is that it detects very small changes in gas content by comparing the varying pressures between circuit breakers. The algorithm detects leaks in the order of 0.1%/year within 2–3 weeks based on absolute pressure reading only. The total installation cost is approximately 750 EUR per sensor.