What are the SF6 gas leak detection methods of GIS equipment?- SF6在线监测系统_SF6检漏仪_SF6传感器_SF6密度继电器

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What are the SF6 gas leak detection methods of GIS equipment?

发布时间：2018-11-06 来源：ydlcb 浏览次数：36次

What are the SF6 gas leakage detection methods for GIS equipment

SF6 gas is an important commissioning item of SF6 circuit breaker and the key to ensure normal operation of SF6 circuit breaker. For equipment in operation, the density relay is generally used to monitor the leakage of SF6 gas in real time. Once the pressure value drops rapidly or an alarm signal appears, it is necessary to further find out the leakage part so as to determine the leakage part in the shortest time and save time for defect treatment. The common leak detection methods are introduced below.

Qualitative leak detection

Qualitative leak detection is practical on site, including simple qualitative leak detection, pressure drop method, segmentation and location method and local accumulation method.

(1) Simple qualitative method. Inspect all assembled sealing surfaces, pipe connections, and other suspect locations with a general leak detector. The method is simple and can find obvious local leakage.

(2) Pressure drop method. Measure the SF6 gas pressure with a precision pressure gauge, retest it every several days or dozens of days, and judge the pressure drop occurred by temperature conversion or transverse comparison.

(3) Segmented location method. It is applicable to the circuit breaker connected with three-phase SF6 gas circuit. The SF6 gas system is divided into several parts and then leak detection is carried out to reduce the blindness.

(4) Local accumulation method: wrap the measuring part with plastic cloth. After several hours, measure whether there is leakage of SF6 gas in the plastic cloth with SF6 leakage detector, which is a commonly used qualitative leakage detection method at present.

Quantitative leak detection

Quantitative leak detection method is to cover the tested switch component or the whole switch with a plastic bag, measure the concentration of SF6 gas in the plastic bag after a certain time (for example, dozens of hours), and then calculate the leakage rate according to the volume in the plastic bag and the surrounding time and other parameters.

Quantitative leak detection includes bottle hanging leak detection method and local wrapping method, which shall be carried out 24h after inflation. WINFOSS-C1 SF6 quantitative leak detector can be used for quantitative measurement, which is safe, convenient and ideal. The judgment standard for quantitative measurement is that the annual air leakage rate is not more than 1%.

The operation practice has proved that the leakage parts of SF6 circuit breaker mainly include: each detection port, welding seam, gas nozzle, flange joint surface, pressure gauge connecting pipe, sealing base, etc. The common air leakage points of GIS equipment include weld joint, air nozzle, flange joint surface and pressure gauge.

Optical imaging leak detection

Optical imaging method is a new technology emerging in recent years. Relatively mature methods include laser imaging method and infrared imaging method, both of which utilize the infrared absorption characteristics of SF6 gas to make the leaked gas clearly visible in the field of view and detect when the equipment is charged.

Infrared imaging method uses the specific infrared absorption spectrum of SF6 gas to make the leaked gas clearly visible, so as to detect the leakage under the condition that the equipment is not powered off. It is an ideal leakage detection method. However, in practice, optical imaging method has some disadvantages due to the installation characteristics of GIS equipment. For example, due to compact installation of indoor GIS equipment, it is difficult to detect internal leakage. For outdoor GIS equipment, due to the high installation height, it is also difficult to detect leakage at the top, edge or hidden place of the equipment. In addition, under the influence of outdoor wind speed, temperature and humidity and other environmental factors, some GIS equipment with slight leakage are more difficult to be detected by optical imaging method.