GB/T 8905-1996 Guidelines for gas management and detection in sulfur hexafluoride electrical equipment
Some standard content:
GB/T8905--1996
This standard is the first revision of GB8905--886 "Guidelines for the management and detection of sulfur hexafluoride gas in electrical equipment" based on the International Electrotechnical Commission 1EC480:1974 "Guidelines for the inspection of sulfur hexafluoride gas in electrical equipment" and IEC376:1971 "Specifications and acceptance of new sulfur hexafluoride" and the supplement of IEC376A:1973.IEC376B:1974. This standard is equivalent to the International Electrotechnical Commission IEC standard in terms of technical content.
The difference between this standard and IEC480 and IFC376 in terms of writing is that Chapter 7 "Safety management of sulfur hexafluoride gas in equipment\ and Chapter B\Testing standards and cycles" is added. The main contents of the previous version are as follows:
1. The density of sulfur hexafluoride gas in Chapter 3 is changed to 6.16 g/L at room temperature and pressure according to EC376 and IEC480.
2. The humidity of the gas in the sulfur hexafluoride equipment in Chapter 8 changes with the temperature, so it is stipulated that the measurement and conversion are carried out at 20℃.
3. The determination of the impurity content of sulfur hexafluoride adopts the traceability method of Articles 4.2, 4.4.4.5.4.6 and 4.7 of GB12022. They are listed in Chapter 9.
4. This standard retains the IEC foreword and adds a foreword. This standard will be implemented from November 1, 1997. From the date of implementation, this standard will replace GB 8905-88. This standard was proposed by the Ministry of Electric Power Industry.
The technical committee for standardization of high-voltage switchgear of the Ministry of Electric Power Industry in this standard is the same as the standard. The revision work of this standard GB8905-88 is composed of the following units: Electric Power Research Institute of Ministry of Electric Power Industry
North China Electric Power Research Institute
Chaming Chemical Research Institute of Ministry of Chemical Industry
Xi'an Thermal Engineering Research Institute of Ministry of Electric Power Industry
Yangtze River Water Conservancy Commission
Xi'an High Voltage Electrical Equipment Research Institute
Wuhan Iron and Steel Company
Main drafters of this standard
Jin Yaozhu
Liu Hangou
Zhu Fangfei
Shao Changpu
Meng Yuchan
Lu Beidou
Zhao Longfei
Liu Liangqiu
Jin Yaozhu
This standard was first issued in March 1988 and revised for the second time in December 1996. ..comGB/T 8905—1996
IEC Foreword
1. The provisions on IEC related technical issues are proposed by professional representatives of all national committees of the technical committee. As far as possible, the international consensus on this subject is obtained. 2. This resolution is based on the recommendation of the United States and is recognized by international organizations. 3. In order to promote international unification, IEC hopes that all national committees will adopt this text as a national standard. The standards introduced by EC are within the scope allowed by the international environment. Any differences between the standards recommended by IEC and the countries should be clearly stated in the national standards.
This standard was drafted by LEC Technical Committee 10C: "Liquid and Gaseous Insulating Materials". The draft was discussed in Tehran in 1969 and in Brussels in 1970, and was sent to the International Committee for approval in September 1971. The IEC International Committee proposed to modify Chapter 7 of Document No. 376. Chapter 9 was approved in January 1973. Chapter 7 A meeting was held in Ljubljana in May 1972 to discuss whom to criticize. The countries participating in the international committee voting are as follows: Australia, Germany, South Africa, Belgium, Israel, Sweden, Canada, Italy, Switzerland, (former) Czechoslovakia*, Japan, Turkey, Denmark, the Netherlands, (former) Soviet Socialist Union", Egypt, Portugal, the United Kingdom, France, Romania. This standard complies with the applicable parts of 1EC480:1974 "Guidelines for the inspection of sulfur hexafluoride gas in electrical equipment". The inspection of sulfur hexafluoride gas impurities is in accordance with the applicable parts of IEC376:1971, 376A:1973, 376B:1974 "Specifications and acceptance of new sulfur hexafluoride". *The (before) before the country name is added by the editor.
..com1 Scope
National Standard of the People's Republic of China www.bzxz.net
Gas Management and Inspection Guidelines for Sulfur Hexafluoride Electrical Equipment
The gulide for processing and measuringSF gas in pover apparatus
GB/T 89051996
neqJEC480:1974
TEC 376:1971
Generation GB8905-88
1.1 This guideline mainly provides gas management and inspection methods for the user departments of sulfur hexafluoride electrical equipment. 1.2 This guideline is applicable to the gas detection in the electrical equipment in operation by the user departments. 1.3 This guideline is a general guideline. Some specific provisions for the inspection and management of sulfur hexafluoride gas in electrical equipment shall be implemented in accordance with other relevant standards.
2 Cited standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and the parties using this standard should discuss the possibility of using the latest versions of the following standards GB5832.1—86 Determination of trace moisture in gas by electrolytic method GB5832.2—86 Determination of trace moisture in gas by dew point method GR11 605—89 Humidity measurement method
GB11023--89 High-voltage switchgear sulfur hexafluoride gas sealing test method GB12022--89 Industrial sulfur hexafluoride
DL506—92 Field measurement method for moisture content in sulfur hexafluoride gas insulation equipment 3 General properties of sulfur hexafluoride gas
3.1 Physical properties
The molecular formula of sulfur hexafluoride gas is SF. , the molecular weight is 146.07, and the molecular diameter is 4.56×10-1°m. Sulfur hexafluoride gas is gaseous at room temperature and normal pressure, and its density at 20℃ and 101325Pa is 6.16/L (about 5 times that of air). The critical temperature of sulfur hexafluoride gas is 45.6℃. It is liquefied by compression and is usually transported in liquid cylinders. Its saturated vapor pressure curve is shown in Figure 1,
For explanation:
The door is IEC 480, IEC 376 physical properties. Approved by the State Administration of Technical Supervision on December 13, 1996, and implemented on November 1, 1997
GB/T8905-1996
Critical temperature
Absolute pressure (×10°P)
1 Saturated vapor pressure curve of sulfur hexafluoride
Pure sulfur hexafluoride gas is colorless, odorless, non-toxic and non-flammable. 3.2 Electrical properties
3.2.1 Sulfur hexafluoride is an electronegative gas (with the ability to absorb free electrons) with good arc extinguishing and insulation properties. In a uniform electric field under a pressure of 101.3kPa, the voltage intensity of sulfur hexafluoride gas is about 2.5 times that of nitrogen. 3.2.2 Pure sulfur hexafluoride is an inert gas that will decompose under the action of an electric arc. When the temperature reaches above 4000K, most of the decomposition products are single atoms of sulfur and fluorine. After the arc is extinguished, most of the decomposition products recombine into stable sulfur hexafluoride molecules. A very small amount of the decomposition products react chemically with free metal atoms, water and oxygen during the recombination process to produce metal fluorides and oxygen-sulfur fluorides.
4 Types of impurities and their effects
4.1 Types of impurities
4.1.1 Fresh gas impurities and their allowable contents shall comply with the quality standards specified in Table 1. Table 1 Quality standard of sulfur hexafluoride
Indicator name
Tetrafluoride (CF)
Gas (N, 0)
Humidity (H2O)
Acidity (in terms of HF)
Hydrolyzable oxide (in terms of HF)
≤0.05% (mass fraction)
≤0.05% (mass fraction)
sg8 μg/g
Indicator name
Mineral powder
Purity (SFe)
GB/T 8905—1996
Table 1 (end)
10pg/g
≥99.8% (mass fraction)
Biological test non-toxic
4.1.2 The sulfur hexafluoride gas in the running electrical equipment contains a variety of impurities. The diffusion of residual moisture inside the electrical equipment will cause the content of air and water to exceed the corresponding initial value of the new gas. The electricity decomposes part of the sulfur hexafluoride, which can produce oxygen-containing, sulfur fluoride and other gases. And solid decomposition products.
4.2 Effect of impurities
Certain impurities (such as nitrogen) have no significant effect on insulation and arc extinguishing performance when their content is low. The content of other types of impurities must be limited so that they will not cause operating accidents to equipment using these gases, whether they exist alone or in combination. For example: water, acidic impurities and oxygen (especially when mixed together) will accelerate corrosion and cause mechanical failure. When water and any acidic impurities are mixed together, they will cause harm to the safety of the equipment at low temperatures and high pressures. Therefore, the content of these impurities must be limited to prevent corrosion and condensation. 4.3 Allowable content of impurities
There is no clear regulation on the allowable (impurity) limits of impure gases, because they depend to a large extent on the design and installation location of the electrical equipment, such as the following: minimum flashover distance, leakage path length, the existence of arcs in closed systems, the properties of components in contact with the gas, absorption capacity, etc. The requirements for humidity in electrical products shall be implemented in accordance with the provisions of 8.1.2. The content of other impurities shall be determined by the design department and the user department based on specific circumstances.
4.4 Toxic impurities
When sulfur hexafluoride is used in electrical equipment, it can decompose, either in a fault condition or under the action of a positive on-off arc, to produce oxygen, sulfur fluoride and metal fluoride powder. Experience shows that workers will feel a piercing or uncomfortable odor in an environment containing even very small amounts of decomposition products, which will cause obvious irritation to the nose, mouth and eyes. This reaction will occur within a few seconds before there is an obvious poisoning reaction. 5 Sampling method
5.1 Overview
The purpose of sampling is to obtain a representative gas sample. In general, SF. exists in a gaseous state, and the sample should be extracted directly from the inside of the equipment, and should not be extracted through the internal expansion device of the equipment. 5.2 Sampling container8
It is ideal to pass the gas sample directly from the equipment to be tested into the analysis device. For items that cannot be directly tested at the operation site, containers made of inert materials are used for sampling.
When the sample is in liquid state, the sampling container must be subjected to a 7MPa pressure test and must not be filled. The filling operation shall comply with the provisions of 6.1 and 6.2 of GB1202289.
The dirtiness of the sampling container increases the impurities in the sample being tested. The sampling bottle shall not be used to hold other substances except sulfur hexafluoride. After the container is used, it shall be heated to 100℃ and vacuumed. Filled with new sulfur hexafluoride to normal pressure and washed at least twice. When stored, it shall be filled with new sulfur hexafluoride gas slightly higher than the atmospheric pressure. Before sampling, vacuumize again with a vacuum pump and rinse the container with the sample to be taken. Sampling instructions:
1) The protective measures in 3.7 of EC480 are in 7.1 of G18905. 271 4.9 of EC480, 5.2 of GB8905 + shall be implemented in accordance with 6.1 and 6.2 of CB12022. ..com5.3 Sampling tube and connection 1
GB/T8905-1996
The sampling tube is a polytetrafluoroethylene tube or stainless steel tube that connects the sampled equipment or sampling container to the analysis device. The inner diameter of the sampling tube is 3~6mm, and the length should be as short as possible. The joint should be all-metal type, such as crimping type or welding type. The inside of the tube should be cleaned and grease, desiccant, etc. should be removed.
The sampling point should be dried and kept clean. The connecting pipeline should ensure that the seal is intact. Before sampling, slowly flush the sample pipeline with sulfur hexafluoride gas and then connect the sample.
6 Identification of gas?
When it is doubted whether the gas in the equipment is all sulfur hexafluoride, and when the spare sulfur hexafluoride gas is difficult to identify with other gases, the method of measuring gas density and the method of measuring thermal conductivity can be used for identification. 6.1 The density determination shall be carried out according to the density determination method of new sulfur hexafluoride gas. 6.1.1 Principle of the method
Accurately weigh the mass of a known volume of gas and calculate its density. 6.1.2 Apparatus
Use a glass spherical bottle or cylindrical bottle with vacuum pistons at both ends. The capacity is about 100 mL. A slightly larger bottle can also be used as long as the balance can handle it and it is within the allowable range of daily weighing.
6.1.3 Calibration of glass spherical volume
Weigh the empty spherical bottle to within ±0.1 mg. Then fill it with distilled water under similar temperature conditions and weigh it again. The difference between the two weighings is the weight of water, that is, the volume of the spherical bottle at this temperature. Note: It is not necessary to calibrate the volume for silicate glass bottles. 6.1.4 Procedure
Carefully dry the spherical bottle, then evacuate the vacuum and weigh it to within ±0.2 mg. Cool the spherical bottle to a temperature slightly lower than the ambient temperature, then fill the spherical bottle with sulfur hexafluoride, keep the spherical bottle filled with gas at room temperature, then quickly open the piston to make the gas in the spherical bottle consistent with the atmospheric pressure, record the temperature and pressure at that time, and then weigh the spherical bottle.
Note: Care should be taken to ensure that the gas fills the spherical bottle. The gas can be filled at a speed of 51./min, and it can be filled in one minute. Note: When evacuating and filling SF gas, these two operations must take appropriate safety measures. 6.1.5 Calculation of results
r=1 000 m
where r——density, kg/m;
m——weight of the spherical bottle when filled with SF,
m.——weight of the spherical bottle after evacuation·gtV-gas volume, which is corrected to the temperature and pressure under standard conditions (20'C, 101325 Pa) by the temperature and pressure measured when adjusting the pressure of the spherical bottle. Measured in mL
6.2 Determination of thermal conductivity
The measurement of thermal conductivity is the most convenient method for on-site identification of sulfur hexafluoride gas. 6.2.1 Principle
The characteristic of thermal conductivity determination is that the thermal conductivity cell is composed of a Wheatstone bridge composed of two heat source detector elements and two matching reference elements, and the two are used as follows:
11 IEC480 4,10, GB8905 5.3. Zengbansan tetrafluoroethylene pipe. 211EC.481 5.11. This standard does not use infrared spectroscopy for identification. GB/T8905—1996
A detector element and two matching reference elements are reversed to obtain an unbalanced signal. In particular, the detector element or the reference element is first contacted with the reference gas (usually ordinary atmosphere), and the bridge is adjusted to a balanced state. After combustion, the gas to be measured passes through the two detector elements. Since the gas to be measured has different thermal conductivity heat consumption rates, the resistance of the detector element changes, and the resulting imbalance is a function of the change in thermal conductivity. 6.2.2 Identification method
The instrument should be operated in accordance with the manufacturer's instructions. Before use, the instrument should be calibrated with pure hexafluoride. Note
1 When calibrated with a standard mixture of hexafluoride and air, the thermal conductivity measuring device can also be used to approximately identify the composition of similar compounds obtained from the equipment.
The thermal conductivity of sulfur hexafluoride is much lower than that of air and nitrogen, so it is possible to clearly distinguish between these gases. Since the thermal conductivity of carbon dioxide is between air, nitrogen and sulfur hexafluoride, if there is a possibility of mixing between carbon dioxide and air and sulfur hexafluoride mixed gas, other methods should be used for identification. For example, carbon dioxide can be identified by a test tube filled with corresponding chemical reagents. 7 Safety management of sulfur hexafluoride gas in equipment 7.1 Quality supervision of new gas
Before filling electrical equipment, it must be confirmed that the quality of sulfur hexafluoride gas is qualified and has a gas factory certificate. If there is no certificate, sampling and re-inspection must be carried out before filling electrical equipment. Filling can only be carried out after confirming that the quality is qualified. The number of bottles sampled meets the requirements of 5.4.2 in GB12022, and the method and steps of re-inspection shall be carried out in accordance with the determination method of sulfur hexafluoride gas impurities in Chapter 9. Note: The contents of 7.1, 7.2 and 7.3 are added on the basis of the original GB8905-88. 7.2 Filling of sulfur hexafluoride gas
7.2.1 During the filling operation, in order to prevent the introduction of foreign impurities, all pipelines and connecting parts must be washed with dilute hydrochloric acid or dilute alkali according to the possible residual dirt and material conditions before filling. After rinsing, heat and dry for standby use. When connecting the temporary line, the operator should wear smooth, clean and dry gloves. Wipe the interface clean and blow dry, and slowly flush the pipe with new sulfur hexafluoride gas to officially fill. 7.2.2 Vacuuming the equipment is an important means of purification and leak detection. Before filling, the equipment should be evacuated to the specified index, the vacuum degree is 133×10-MPa, and then continue to evacuate for 30 minutes. Stop the pump for 30 minutes and record the true longitude (A). After 5 hours, read the vacuum degree (B). If the value of (B) minus (A) is 133X10-MPa, it can be considered qualified. Otherwise, it should be processed and re-evacuated until it is qualified. 7.2.3 Before filling the equipment with new sulfur hexafluoride gas, the humidity should be checked again. Only when it is confirmed to be qualified can it be filled slowly. When the pressure of the sulfur hexafluoride gas cylinder drops to 0.1 MPa gauge pressure, the filling should be stopped. 7.2.4 After filling, conduct a comprehensive inspection of the equipment seals, welds and pipe joints. If there is no leakage, the filling is considered complete. 7.2.5 24 hours after filling, measure the humidity of the gas in the equipment. If it exceeds the standard, it must be processed until it is qualified. 7.3 Supervision and management of hexafluoride gas quality during operation 7.3.1 The equipment installation room should be regularly ventilated and the sulfur hexafluoride and oxygen content should be regularly inspected. The oxygen content in the air should be greater than 18%.
7.3.2 Indoor equipment areas where operators frequently enter and exit should be ventilated for at least 15 minutes per shift, and the maximum ventilation should be 35 times the volume of the space. The exhaust port should be placed in the lower part of the room. Equipment places where staff do not frequently enter and exit should be ventilated for 15 minutes before entering1. 7.3.3 Oxygen meters and sulfur hexafluoride concentration meters with alarm devices should be installed on the ground floor of the equipment installation site. The oxygen content in the air should be greater than 18%. The oxygen meter should alarm when the oxygen content in the air drops to 18%. The sulfur hexafluoride concentration meter will sound an alarm when the sulfur fluoride content in the air reaches 1000μL/L. If unqualified, ventilation and air change should be carried out. 7.3.4 If the gauge pressure drops during equipment operation and the air replenishment alarm sounds, the cause should be analyzed. If necessary, the equipment should be fully leak-checked and effectively handled. If gas points are found, they should be handled immediately. 7.3.5 The humidity in sulfur hexafluoride gas is a key indicator affecting the safe operation of equipment. If the humidity is found to exceed the standard, a gas recovery device should be used for drying and purification.
Instructions for use:
11EC480, 1EC376 do not contain Chapter 7, GB/T8905-1996
7.3.6 The amount of adsorbent added to sulfur hexafluoride electrical equipment can be 1/10 of the weight of the gas filled. 7.4 Safety management during equipment dismantling
Sulfur hexafluoride gas decomposes into gaseous and solid by-products under the action of electricity. These products are harmful and corrosive. Safety must be paid attention to during operation.
7.4.1 Before the equipment is dismantled, it is necessary to discharge and treat the used sulfur hexafluoride gas, which may contain a large amount of harmful substances. Strict supervision and management measures must be implemented to prevent poisoning accidents. Before dismantling, the gas needs to be fully analyzed to determine the content of its harmful components. The degree of toxicity can be determined by the method of gas toxicity biological test, and then anti-toxic measures can be formulated. 7.4.2 Before dismantling the equipment, all sulfur hexafluoride gas shall be recovered through the gas recovery device. The recovered gas shall be placed in a clearly marked container for treatment. If the residual gas is released into the atmosphere, it must be subjected to anti-toxic adsorption to prevent the emission of toxic gas into the atmosphere. 7.4.3 After the equipment is dismantled, the maintenance personnel shall immediately leave the work site and go to a place with fresh air. The work site needs strong ventilation to clean up the residual gas and work shall be resumed at least 30 to 60 minutes later. 7.4.4 Sulfur hexafluoride electrical equipment contains toxic or corrosive powders. Some solid powders are attached to the equipment and the surface of the original parts. These powders should be carefully cleaned up and disinfected with a special vacuum cleaner. The items used for disinfection need to be soaked in a sodium hydroxide solution with a concentration of about 20 and then buried deep.
7.4.5 When maintenance personnel come into contact with decomposition gas and dust, they should wear work clothes made of acid-resistant materials, plastic or soft rubber gloves, and special respirators. Operators should pay attention to cleaning after work. 7.4.6 When sulfur hexafluoride electrical equipment fails and gas escapes, personnel should immediately evacuate the site and immediately take strong ventilation. The ventilation time shall not be less than 15 minutes. After an accident, anyone entering the room must wear protective clothing, gloves and a gas mask. When a fault occurs, if someone is attacked by the escaped gas, he/she should take off his/her work clothes and go to the hospital for treatment. 7.4.7 When the humidity of the recovered sulfur hexafluoride gas does not meet the standard value of the new gas quality after analysis, it must be purified and can be reused after confirmation of compliance.
7.5 Pipe burial of adsorbent
The type and amount of adsorbent in the equipment should comply with the manufacturer's regulations. 7.5.1 Installation of adsorbent
The adsorbent should be activated before installation. The time from taking the adsorbent out of the dry coal container or the sealed container to the completion of installation should be shortened as much as possible. Generally, it should not exceed 15 minutes. After the adsorbent is installed, it should be vacuumed immediately within 30 minutes. 7.5.2 Treatment of adsorbents
When the adsorbent needs to be activated, the treatment temperature should be 500~600℃. The adsorbent replaced in the equipment for generating decomposition gas should not be regenerated. It should be soaked in 20% sodium hydroxide solution and buried deep. 7.5.3 Storage of adsorbents
The adsorbent should be moisture-proof and waterproof and stored in a dry place. 7.6 Safety management of sulfur hexafluoride containers
7.6.1 Requirements for the production of sulfur hexafluoride gas The fluoride manufacturer should provide a chemical analysis report of the product leaving the factory. The report should include 8 indicators: carbon tetrafluoride (CF.), air (Ait), water (HO), acidity, hydrolyzable fluoride, mineral oil, purity (SF,) and biological test non-toxic certificate. These indicators should be placed together in the gas cylinder cap when the product leaves the factory.
7.6.2 Requirements for sulfur hexafluoride gas containers7.6.2.1 Pressure vessels filled with sulfur hexafluoride must have the inspection mark of pressure vessels issued by the national accreditation department before they can be used. 7.6.2.2 Containers filled with sulfur hexafluoride must be vacuum treated before filling to make them free of oil and moisture. 7.6.2.3 The safety accessories of the pressure vessel must be complete, and the valve body and the connection between the container must be sealed and leak-free. 7.6.3 Rules to be followed when filling gas
Sulfur hexafluoride is a compressible liquefied gas. When filling in a compressed gas, the filling coefficient when the cylinder design pressure is 8.0MPa shall not be greater than B/T8905-1996
1.17kg/L. The filling coefficient when the cylinder design pressure is 12.5MPa shall not be greater than 1.33kg/L. It is strictly forbidden to overfill, and the filling weight must be rechecked strictly. Cylinders filled with excessive gas should not be pushed to the factory. Filling records must be filled carefully (including date, batch number, gross weight, actual filling volume, signatures of the filler and rechecker).
7.6.4 Transportation, acceptance, and storage safety management of sulfur hexafluoride gas cylinders 7.6.4.1 When storing sulfur hexafluoride gas cylinders, there must be sun-proof and moisture-proof covering measures, and they must not be close to heat sources or places with oil stains. Safety helmets and shockproof rings must be complete. Gas cylinders must be stored in categories and marked with obvious signs. Gas cylinders must be stored vertically with the signs facing outwards, and can be placed horizontally during transportation. 7.6. 4.2 New sulfur hexafluoride should be accompanied by a factory card and accepted according to quality standards. 7.6.4.3 After use, sulfur hexafluoride gas cylinders must retain residual gas, close the valves, and cover the caps. 7.6.4.4 The place where gas cylinders are stored must be spacious and well ventilated. 8 Inspection standards and cycles 1
8.1 Inspection standards
8.1.1 The standard for the new sulfur hexafluoride gas is shown in Table 1.8.1.2 The allowable value of the gas humidity of the sulfur hexafluoride equipment at 20°C is shown in Table 2 (converted according to the temperature and humidity curve provided by the equipment manufacturer). Note: Add SF6 in GB 8905; the allowable value of the gas humidity of the equipment at 20°C, Table 2
Acceptance value
Operation allowable value
Compartment with arc decomposition
Especially the compartment with arc decomposition
Note: The allowable value of humidity of the sulfur hexafluoride equipment with a gas pressure below 0.1MP# gauge pressure can be relaxed. To be agreed upon by the supply and demand parties 8.1.3 The annual gas leakage rate of each compartment of the sulfur hexafluoride equipment shall not exceed 1%. Note: The reference value of 3% per year is specified in GR8905-88, which is cancelled after revision. 8.1.4 Limit value of sulfur hexafluoride gas concentration in the operating room air. 8.1.4.1 The allowable concentration of sulfur hexafluoride gas in the air shall not exceed 1000uL/L; or (6g/m). 8.1.4.2 For short-term contact, the allowable concentration of sulfur hexafluoride in the air shall not exceed 1250mL/L or (7.5g/m). 8.2 Inspection cycle
8.2.1 Humidity inspection
Measure once every 3 to 6 months after the new equipment of 126~550kV is put into operation. If there is no abnormality, it can be measured every 1 to 2 years. For 40.5~72.5kV equipment, after it is put into operation, it shall be re-inspected once a year. If there is no abnormality, it can be measured once every 2 to 3 years. 8.2.2 Leakage detection
Operate according to Chapter 4 of GB11023-89.
8.2.3 Replacement of adsorbent
When the sulfur hexafluoride equipment is overhauled or dismantled, the adsorbent should be replaced. 8.2.4 If the new sulfur hexafluoride gas is stored by the user for more than half a year, the humidity should be measured before use, and the quality should meet the new gas standard. 9 Determination of impurities in sulfur hexafluoride gas
9.1 Determination of humidity in sulfur hexafluoride gas
9.1. 1 Electrolysis method
Instructions for use:
17IEC480:1974,[EC376:There is no standard content in Chapter 8 in 1971. GB/T8905-1996
According to GB5832.1 "Electrolytic method for measuring trace moisture in gas". 9.1.2 Dew point
According to GB5832.2 "Dew point method for measuring trace moisture in gas".
9.1.3 Negative volume method
According to DI.506 "On-site measurement method for moisture content in sulfur hexafluoride gas insulation equipment". 2 Determination of air and carbon tetrafluoride content
According to 4.2 of GB12022.
9.3 Determination of acidity
According to 4.4 of GB12022
9.4 Determination of hydrolyzable fluoride
According to 4.5 of GB12022.
9.5 Determination of mineral oil
Determine according to 4.6 of GB12022.
9.6 Biological test for toxicity of sulfur hexafluoride gas
Determine according to 4.7 of GB12022.
When calculating, the density of sulfur hexafluoride at 20C+101,3 kPa in GH 12022 is changed to 6.08 g/L, the density of sulfur hexafluoride at 20C.,101325P: 1
6.16 g/L.
Chapter 8 of GR 8905-88 is deleted, and the methods of 4.2, 4.4, 4.5, 4.6, 4.7 of GB 12022 are used for determination. The sensitivity is determined by CB 5832.1, 2
GR 6832.2.DI.506-92.
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