I. Core Application Scope
The SF6 micro-water tester is mainly used for quantitative measurement of the moisture content in SF6 gas. The specific application scenarios are as follows:
Insulation Performance Evaluation
Water can react with the toxic by-products decomposed by SF6 under the action of electric arcs, generating corrosive acids, which significantly reduces the insulation strength of electrical equipment and may cause equipment breakdown or explosion. Monitoring the moisture content is a key measure to ensure the safe and stable operation of equipment.
Equipment Condition Diagnosis
The moisture content is an important indicator reflecting the internal operating status of SF6 electrical equipment (such as GIS, circuit breakers, etc.). If the moisture content exceeds the standard, it may indicate the following problems:
Sealing components of the equipment show signs of aging;
Adsorbents reach saturation and lose their adsorption efficiency;
There are gas leakage points in the equipment;
The gas drying treatment in the last charging or replenishment operation was not thorough.
New equipment commissioning and maintenance acceptance
After new equipment is installed and charged, or after major maintenance of the equipment, the moisture content of SF6 gas must be measured to confirm that it meets the national standards and relevant regulations before being put into formal operation.
Preventive Maintenance
By regularly monitoring the trend of moisture content changes, it is possible to predict potential fault hazards of the equipment in advance, helping to achieve the transformation of the equipment maintenance mode from “post-event repair” to “preventive maintenance”.
II. National and Industry Standards Followed
The operation of the SF6 micro-water tester, instrument calibration, and moisture content limits for SF6 electrical equipment all need to follow a series of strict national and industry standards. The specific classification is as follows:
Equipment Moisture Content Limit Standards (Testing Basis)
GB/T 12022-2014 “Industrial Sulfur Hexafluoride”: Clearly stipulates the moisture content requirements for new SF6 gas, which must meet ≤5 ppmV (corresponding to dew point – 49.7℃).
DL/T 603-2017 “Operation and Maintenance Regulations for Gas-Insulated Metal-Enclosed Switchgear”: As the core basis for determining the moisture content of operating equipment, different voltage levels and different types of gas chambers (circuit breaker gas chamber / non-circuit breaker gas chamber) have specified the allowable moisture content values under commissioning acceptance and operating conditions (unit: ppm (V/V)).
Taking the allowable values under operating conditions as an example:
Gas chambers with arc decomposition products (such as circuit breaker gas chamber): Moisture content ≤300 ppm;
Gas chambers without arc decomposition products (such as busbar gas chamber, disconnect switch gas chamber): Moisture content ≤500 ppm.
It should be noted that the moisture content limit in the commissioning acceptance stage is more stringent than the allowable values under operating conditions.
Instrument Calibration Procedures (Ensuring Instrument Accuracy)
JJG 500-2005 “Calibration Procedure for Electrolytic Humidity Meters”: Applicable to SF6 micro-water testers based on electrolytic principles.
JJG 826-1993 “Calibration Procedure for Resistance-Capacitance Dew Point Hygrometers”: Applicable to SF6 micro-water testers based on resistance-capacitance principles.
These procedures clearly specify the calibration conditions, calibration items, calibration methods, and calibration cycles (usually 1 year) of the instrument to ensure the accuracy and reliability of the value transfer.
Field Testing Method Standards
DL/T 506-2018 “Measurement Method for Insulation Gas Moisture in SF6 Electrical Equipment”: As a guiding standard for field testing operations, it provides detailed specifications for the entire testing process, including:
Testing conditions (such as environmental temperature, environmental humidity, etc.);
Testing cycle requirements;
Technical indicators requirements for SF6 micro-water testers;
Standard test connectors and pipeline connection methods;
Specific measurement steps and operation precautions;
Calculation methods and report formats for measurement results. The on-site test operators must undergo professional training and carry out the testing work strictly in accordance with relevant regulations such as DL/T 506, in order to ensure the accuracy of the measurement results and avoid the potential hazards brought by SF6 gas and its decomposition products, thus safeguarding the safety of personnel and equipment.
Post time: Dec-09-2025