Does the SF6 alarm device need to be installed in the cable trench of the high voltage substation?- 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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Does the SF6 alarm device need to be installed in the cable trench of the high voltage substation?

发布时间：2020-09-23 来源：ydlcb 浏览次数：26次

SF6 gas is almost the insulation and arc extinguishing medium in high voltage and ultra-high voltage circuit breakers and GIS. Pure SF6 gas is colorless, tasteless, non-flammable, and has particularly stable chemical properties at room temperature, which is more than 5 times the specific gravity of air. However, in the power system, SF6 gas mainly acts as insulation and arc extinguishing medium, under the influence of arc, partial discharge, high temperature and other factors, SF6 gas will decompose. Its decomposition produces corrosive electrolytes after water, especially some highly toxic decomposition substances, such as SF4, S2F2, SOF2, HF, SO2, etc., such as large inhalation of human body will cause dizziness and pulmonary edema, and even coma and death.

SF6 is an asphyxiant that, in high concentrations, causes difficulty breathing, wheezing, blue skin and mucous membranes, and generalized convulsions. After inhaling a mixture of 80% sulfur hexafluoride and 20% oxygen for a few minutes, the human body will experience numbness in the limbs and even suffocation. China stipulates that the allowable concentration of sulfur hexafluoride gas in the air in the operation room should not be greater than 6g/m3 or the oxygen content in the air should be greater than 18%; For short-term exposure, the allowable concentration of sulfur hexafluoride gas in the air is not greater than 7.5g/m3. Sulfur hexafluoride is an inert gas in mechanism, low toxicity but has asphyxiating effect on human body. In the course of life or use, some trace amounts of toxic sulfur of low fluorine compounds and fluorine oxides will be broken down.

In a relatively sealed room, due to poor air circulation, SF6 and its decomposition are deposited in the room, and SF6 gas is colorless and tasteless, which causes great harm to inspection and maintenance personnel. When GIS leaks, SF6 gas accumulates in the lower floor space, causing local hypoxia, causing suffocation and causing a major accident. However, in the "Electrical industry safety Work Regulations" (power plant and substation part) and related requirements do not mention the installation of SF6 monitoring probes and oxygen meters in the cable trench, but for safety reasons, 1 to 2 SF6 monitoring and oxygen monitoring probes are properly installed in a reasonable position in the low area of the relatively dry cable trench and cable interlayer.

SF6 alarm device installation in accordance with the "DL408-1991 electrical industry safety work regulations (Electrical parts of Power plants and substations)" Chapter 8, "DLT 639-1997 sulfur hexafluoride electrical equipment Operation, testing and maintenance personnel safety protection Rules" chapter 4 requirements and "JBT 10893-2008 Environmental monitoring system of sulfur hexafluoride in high voltage combined electrical distribution room. Among them, in the "Electrical industry safety Work Regulations" (power plant and substation part), it is required that the distribution unit room equipped with SF6 equipment must ensure that the SF6 gas concentration is less than 1000ppm, and in addition to the installation of strong ventilation devices, it must also install an alarm oxygen meter and SF6 gas concentration monitoring and alarm meter. SF6 Safety Regulations Excerpt:

Article 191 Power distribution rooms and SF6 gas laboratories equipped with SF6 equipment must be equipped with powerful ventilation devices. The air outlet should be set in the lower part of the room.

Article 192 In the room, when the equipment is filled with SF6 gas, the relative humidity of the surrounding environment is 80%, and the ventilation system must be turned on to avoid SF6 gas leakage in the working area. The SF6 gas content in the working area air shall not exceed 1000ppm.

Article 196 The staff entering the SF6 distribution unit room must first ventilate for 15min, and measure the SF6 gas content with a leak detector, try to avoid one person entering the SF6 distribution unit room for inspection, and no one is allowed to enter the maintenance work.

Article 198 Staff entering the SF6 distribution unit room low area or cable trench to work should first test the oxygen content (not less than 18%) and SF6 gas content is qualified.

Article 199 The oxygen meter and the SF6 gas leakage alarm meter shall be installed in the low area of the SF6 power distribution unit room. These instruments should be tested regularly to ensure their good condition.

Article 203 In the event of an emergency, all ventilation systems shall be opened immediately for ventilation. In the event of a rupture of the equipment's anti-explosion film, it should be treated with power failure and wiped clean with gasoline or acetone.