What are the on- 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 on-site leak detection methods for SF6 circuit breakers?

发布时间：2024-07-05 来源：ydlcb 浏览次数：24次

If the pressure of the field circuit breaker drops abnormally, the leak detection method still has two methods: qualitative and quantitative. The qualitative search of leakage, as with the ordinary SF6 circuit breaker, the instrument should be adjusted to the working state before measurement. The sensitivity is slightly higher, and then pick up the probe and carefully detect the external leakage parts of the equipment, such as: each detection port, weld, inflation nozzle, flange connection, pressure gauge connection tube and sliding seal base. Although the SF6 gas concentration in the leaking gas mixture is only about half of the ordinary SF6 circuit breaker. However, as long as the leakage rate is large, it can still determine the leak location and rough concentration according to the acoustic and optical alarm signals emitted by the detector and the deflection degree of the instrument pointer.

Although there are many kinds of leak detectors, they are usually mainly composed of three parts: probe, detector and pump body, which can alarm the halogen gas detected. The working principle of SF6 gas leak detector is that when there is SF6 gas in the atmosphere, the probe sucks the SF6 gas into the detector diode and generates corona discharge with the help of the suction force of the vacuum pump, so that the current of the diode electrode is reduced, and the signal of the current reduction is converted into an audible and optical alarm signal through the electronic circuit. The stronger the sound and light signal.

(2) The quantitative test of leakage can still be used by hanging bottle leak method, local dressing method or the whole machine buckle method. If the manufacturer of SF6/N2 mixed gas circuit breakers still sets the annual gas leakage rate to be no more than 1%, then this 1% should contain the amount of SF6 and N2 two gases that leak out. In the quantitative test method used to collect leaking gas, the leak detector can only detect the volume concentration K of SF6 gas. Therefore, when calculating the leakage rate formula, it must be multiplied by the coefficient 2(gas mixture of 50% SF6+ 50% N2) or 5/3(gas mixture of 60% SF6+ 40% N2) before K.

1) Bottle pickup method The circuit breaker produced by some manufacturers has a detection port at the flange joint surface, etc. The detection port is connected with the groove outside the sealing ring, which can collect SF6 gas when the sealing ring leaks. When the leakage port has SF6 gas leakage, the bottle can be hung at the detection port.

The leak detection bottle is 1000mL plastic bottle. The screw of the detection port is removed before hanging the bottle. The duration is 24h, so that the accumulated SF6 gas in the detection port is discharged, and then the bottle is hung. The bottle hanging time was 33min, and then the leak detector was used to check the SF6 gas concentration in the bottle.

2) The whole machine buckle cover leak detection method For the smaller 40.5kV and 12kVSF6 circuit breakers can be tested by the whole machine buckle method using the manufacturer's equipped seal cover on site. The upper, middle, lower, front, back, left and right of the sealing cover are provided with appropriate small holes and sealed with adhesive tape as test holes.

3) Local bandaging leak detection method For SF6 circuit breakers with voltage levels of 252kV and above after installation, due to the large volume, the whole buckle cannot be implemented, and the local bandaging method can be used for measurement. In the flange, density relay, switch tie rod dynamic seal, etc., the measured point is covered with plastic cloth, and the formula for measuring air leakage after 24h is to add up the air leakage of each binding point to get the total air leakage ∑Q(the air leakage at the dynamic seal must be multiplied by the average number of times a year), through the leak detection, after determining the leak point, the cause of the leakage should be analyzed. Take corresponding measures respectively. For example: replace leaking pressure gauges, broken porcelain bushings and aging seals.