The SF6 moisture tester is mainly used for quantitatively measuring the moisture content in SF6 gas. Its core application scope includes:
Insulation performance assessment: Water reacts with the toxic by-products formed by the decomposition of SF6 under the action of electric arcs, generating corrosive acids, which significantly reduces the insulation strength of electrical equipment and may lead to breakdown or explosion. Monitoring water content is crucial for ensuring the safe operation of the equipment.
Equipment status diagnosis: The moisture content is an important indicator reflecting the internal condition of SF6 electrical equipment (such as GIS, circuit breakers, etc.). Excessive moisture may indicate:
The sealing parts of the equipment have aged.
Adsorbent saturation failure;
There are leakage points in the equipment.
Last time, the gas was not fully dehydrated during inflation or refilling.
Commissioning and acceptance of new equipment: After the equipment is installed and inflated, or after a major overhaul, the moisture content of SF6 gas must be measured to ensure it complies with national standards and manufacturer specifications before it can be put into operation.
Preventive maintenance: Regularly monitoring the trend of moisture content changes can predict potential problems of the equipment, enabling the transition from "post-event repair" to "preventive maintenance".
SF6 Moisture Tester
The operation, verification and equipment moisture limit values of the SF6 moisture tester are in accordance with a series of strict national and industry standards.
A. Equipment moisture content limit standard (Testing basis)
GB/T 12022-2014 "Industrial Sulfur Hexafluoride": Specifies the moisture content requirements for new SF6 gas (≤ 5 ppmV or -49.7℃ dew point).
DL/T 603-2017 "Operation and Maintenance Regulations for Gas-Insulated Metal-Enclosed Switchgear": This is the most important basis for operating equipment. It stipulates the allowable moisture content (in units of ppm(V/V)) for different voltage levels and different gas compartments (switches/non-switches) during commissioning and operation.
Example (Allowed values during operation):
Gas compartments containing arc decomposition products (such as circuit breakers): ≤ 300 ppm
Gas chambers without arc decomposition products (such as busbars, disconnect switches): ≤ 500 ppm
Note: The handover and acceptance values are stricter than the operating permitted values.
B. Instrument Calibration Procedures (Ensuring the Accuracy of the Instrument)
JJG 500-2005 "Verification Regulations for Electrolytic Humidity Meters": Applicable to instruments based on the electrolytic principle.
JJG 826-1993 "Verification Regulations for Capacitive Resistance Type Dew Point Hygrometer": Applicable to instruments based on the capacitive resistance principle.
These regulations specify the calibration conditions, items, methods and cycles (usually one year) for the instruments, ensuring the accuracy and reliability of the value transmission.
C. On-site Testing Method Standards
DL/T 506-2018 "Measurement Method for Insulation Gas Humidity in SF6 Electrical Equipment": An operation guideline standard for on-site testing. It specifies in detail:
Test conditions (such as environmental temperature and humidity)
Test cycle
Technical Requirements for SF6 Moisture Tester
Standard test connectors and pipeline connection methods
Measurement procedures and precautions
The calculation of results and the format of the report
Operators must undergo training and strictly follow regulations such as DL/T 506 when operating to ensure the accuracy of the measurement results and the safety of personnel and equipment (SF6 gas and its decomposition products may be harmful).
