SF6 Leak Detection Methods for GIS Equipment

For SF6 gas leakage rate detection in GIS equipment, when using the quantitative leak detection method, the initial SF6 gas content in the GIS equipment must be accurately measured. According to relevant standards, the measurement error should be controlled within ±0.5%. The leakage rate is calculated based on changes in gas content after a period of time, thereby evaluating the sealing performance of the equipment.

In qualitative leak detection methods, direct visual inspection is commonly used, which involves visually observing critical areas such as joints and valves of the GIS equipment for signs of SF6 gas leakage, such as frost formation. This requires inspectors to have extensive field experience to accurately identify subtle leakage characteristics. Infrared imaging-based detection techniques utilize the absorption characteristics of SF6 gas at specific infrared wavelengths. During detection, the infrared thermal imager's wavelength should be set around 6 μm, enabling rapid localization of potential leak points in GIS equipment, with detection accuracy reaching ppm levels.

When using the hood method for leakage rate detection, a suitable sealed hood must be custom-made according to the specific dimensions of the GIS equipment. The ratio of internal hood volume to equipment volume is generally controlled between 1.2 and 1.5 to ensure a relatively stable detection environment and thus obtain accurate leakage data.

For gas mass spectrometry in SF6 leakage detection, precise measurement of ion mass and relative abundance enables identification of extremely small amounts of SF6 leakage, with detection limits as low as ppb level, providing strong support for early detection of potential leaks.

When applying the pressure drop method to detect leakage rates, continuous monitoring of internal pressure changes in the GIS equipment is required, with pressure values recorded every 24 hours. The leakage amount is calculated based on the ideal gas law, taking into account the influence of environmental factors such as temperature and pressure during calculation.

Laser scattering method detects SF6 gas leakage by analyzing the scattered light signal generated from the interaction between laser and leaking gas. In practice, the laser output power should be adjusted between 5–10 mW to ensure detection sensitivity and accuracy.

The adsorbent weighing method determines leakage by measuring the weight change of an adsorbent before and after absorbing SF6 gas. Activated alumina is typically used as the adsorbent, which has an adsorption efficiency of 0.2–0.3 g of SF6 per gram of adsorbent at 25°C, allowing calculation of the leakage rate.

Electrochemical detection uses sensors that respond electrochemically to SF6 gas for leak detection. This method typically has a response time within 1–3 minutes, enabling real-time monitoring of SF6 gas concentration around GIS equipment for prompt leak identification.

Ultrasonic detection identifies SF6 gas leaks based on ultrasonic signals generated during gas leakage. During detection, the ultrasonic sensor frequency is generally set between 20–100 kHz, effectively detecting weak ultrasonic signals produced by minor leaks.