By sion932 
Abstract: SF6 gas is widely used in power equipment due to its excellent insulation and arc-extinguishing properties. However, the decomposition products generated by SF6 gas under abnormal operating conditions of power equipment will not only affect the performance of the equipment but also pose potential risks to the safe and stable operation of the power grid. Q-GDW 11304.13-2015, as a key technical specification for SF6 decomposition products live detection instruments in power equipment, plays a crucial role in standardizing the design, production, procurement and inspection of such instruments. This article systematically elaborates on the core content of Q-GDW 11304.13-2015, including the scope of application, technical requirements, test methods, inspection rules, and its application value in power grid operation and maintenance, aiming to provide a comprehensive technical reference for relevant practitioners in the power industry.
1. Introduction
With the continuous development of the power industry, the scale of the power grid is expanding, and the requirements for the safe and reliable operation of power equipment are increasingly high. SF6 gas-insulated equipment has become an important part of the power system, and its operating status directly affects the stability of the entire power grid. The detection of SF6 decomposition products is an effective means to judge the internal fault status of SF6-insulated power equipment. By detecting the types and concentrations of decomposition products such as SO2, H2S, and CO in SF6 gas, potential faults in the equipment can be found in a timely manner, providing a basis for equipment maintenance and fault handling.
Q-GDW 11304.13-2015 “Technical Specification for Energized Test Device of Electrical Equipment – Part 13: Technical Specification for SF6 Decomposition Products Detector” was issued and implemented by State Grid Corporation of China on November 7, 2015. This standard is part of the series of standards “Technical Specification for Energized Test Device of Electrical Equipment”, which specifically targets SF6 decomposition products live detection instruments based on the electrochemical sensor principle. It formulates a complete set of standardized requirements, which is of great significance for improving the quality and detection accuracy of SF6 decomposition products detectors, and ensuring the effectiveness and reliability of live detection work.
2. Scope of Application
Q-GDW 11304.13-2015 specifies the standardized requirements for the working conditions, technical requirements, test methods, inspection rules, marking, packaging, transportation, and storage of SF6 decomposition products live detection instruments (hereinafter referred to as “detectors”). It should be emphasized that this standard is applicable to the design, production, procurement, and inspection of detectors based on the electrochemical sensor principle. For the detection of mixed insulating gas decomposition products, this standard is temporarily not applicable.
3. Core Technical Requirements
The technical requirements of Q-GDW 11304.13-2015 cover multiple aspects such as structure and appearance, functions, performance characteristics, safety, environmental adaptability, and electromagnetic compatibility, which provide comprehensive technical guidance for the research and development and production of detectors.
3.1 Structure and Appearance
The detector’s structure should be sturdy and durable to meet the vibration, impact, and packaging and transportation requirements specified in GB/T 6587—2012. The outer casings of the main unit, sensors, and other key components of the instrument should have no obvious defects, no sharp edges or corners. The surface treatment processes such as electroplating, oxide layer, and paint layer should be of good quality, without delamination or peeling. Each key component should be marked with model, serial number, manufacturer, production date, and other information. The marks on the panel should comply with the requirements of GB 3100 and GB 3101, be clearly printed or engraved, and be able to be retained for a long time. The buttons should be flexible and reliable in operation, without jamming or poor contact.
3.2 Functions
In terms of basic functions, the detector must have data query, storage, and export capabilities. It is advisable to have alarm threshold setting and indication functions, as well as interference suppression functions. If the detector is powered by a rechargeable battery, the battery should be easy to replace, and the continuous working time of a single charge should not be less than 4 hours in general. In terms of special functions, the detector should meet the corresponding technical specification requirements according to the actual application scenarios, ensuring the accuracy and effectiveness of SF6 decomposition product detection.
3.3 Performance Characteristics
The performance indicators of the detector are the core basis for measuring its detection quality, including measurement range, uncertainty, repeatability, etc. These indicators must meet the specific requirements specified in the standard to ensure that the detector can accurately measure the concentration of SF6 decomposition products such as SO2, H2S, and CO in different operating environments, providing reliable data support for equipment fault diagnosis.
3.4 Safety Requirements
The safety of the detector is crucial to the safe operation of power equipment and the personal safety of operators. The detector should comply with the requirements of GB 4793.1—2007. If the power supply voltage exceeds 30V AC (effective value) or 60V DC, the contact current between the outer casing and the ground should not be greater than 3.5mA effective value (sine wave). The detector must be able to withstand a dielectric strength test for 1 minute, and the test voltage should meet the requirements specified in the standard. During the test, there should be no breakdown or repeated arcing, but corona effects and similar phenomena are allowed. It should be emphasized that during the working process of the detector, it shall not change the connection mode, sealing performance, or insulation performance of the main equipment, shall not affect the safe operation of on-site equipment, and shall not interfere with the quality of power communication.
3.5 Environmental Adaptability and Electromagnetic Compatibility
The detector needs to work in various complex on-site environments, so it must have good environmental adaptability. It should be able to withstand the temperature, humidity, vibration, impact, and other environmental tests specified in GB/T 6587—2012 (Group III requirements), and the performance should still meet the standard requirements after the tests. In terms of electromagnetic compatibility, the detector should comply with the requirements of Q-GDW 11304.1—2015, and pass a series of anti-interference tests such as radio frequency electromagnetic field radiation immunity test, electrical fast transient burst immunity test, surge (impact) immunity test, etc. Under the action of external interference, the detector should still be able to work stably and accurately, ensuring the reliability of detection data. In addition, the enclosure protection level of the detector should not be lower than IP31 as specified in GB 4208, to achieve a certain degree of dust and water protection.
4. Test Methods
Q-GDW 11304.13-2015 specifies detailed test methods for each technical requirement of the detector, ensuring the scientificity and operability of the test work.
4.1 Function Inspection
The basic functions of the detector are inspected item by item according to the requirements of the standard, including testing the data query, storage, export functions, alarm threshold setting function, interference suppression function, etc. The special functions are inspected according to the corresponding technical specifications to ensure that all functions can work normally.
4.2 Performance Characteristic Testing
The performance characteristics of the detector, such as measurement range, uncertainty, and repeatability, are tested by professional equipment and methods. During the test, the detector is placed in a standard test environment, and the concentration of SF6 decomposition products is measured multiple times to verify whether its performance indicators meet the standard requirements. For example, when testing the measurement accuracy of SO2 and H2S, standard gas mixtures of known concentrations are used for calibration and verification.
4.3 Safety Test
The safety test includes contact current test, dielectric strength test, etc. The contact current test is carried out by professional current measuring equipment to verify whether the contact current between the detector’s outer casing and the ground meets the standard requirements. The dielectric strength test is carried out by gradually increasing the test voltage to the specified value within 10 seconds and maintaining it for 1 minute, observing whether there is breakdown or repeated arcing phenomenon.
4.4 Environmental Adaptability and Electromagnetic Compatibility Test
The environmental adaptability test is carried out in a professional environmental test chamber, simulating different temperature, humidity, vibration, impact, and other environmental conditions to test the performance stability of the detector. The electromagnetic compatibility test is carried out according to the methods specified in GB/T 17626 series standards, including radio frequency electromagnetic field radiation immunity test (frequency range: 80MHz～3000MHz, test field strength: 10V/m), electrical fast transient burst immunity test (test voltage: 4kV for power port, 2kV for data port), etc..
5. Inspection Rules
Q-GDW 11304.13-2015 specifies strict inspection rules for the detector, including type inspection and factory inspection. Type inspection is carried out when the product is first developed, when the design, material, or process is significantly changed, or when the product is put into production after a long-term suspension. All technical requirements specified in the standard need to be inspected. Factory inspection is carried out for each batch of products leaving the factory, focusing on inspecting the structure and appearance, basic functions, safety indicators, etc. of the detector. Only products that pass the inspection can leave the factory, ensuring the quality of the products put into use.
6. Application Value in Power Grid Operation and Maintenance
Q-GDW 11304.13-2015 provides a unified technical standard for SF6 decomposition products detectors, which has important application value in power grid operation and maintenance. By using detectors that meet the standard requirements, operation and maintenance personnel can carry out live detection of SF6-insulated power equipment, timely find potential faults such as internal discharge and overheating of the equipment, and avoid major accidents such as equipment damage and large-area power outages.
In actual power grid operation and maintenance, there have been many cases where live detection based on standard-compliant instruments has successfully avoided major accidents. For example, during the UHF detection of a 500kV substation’s GIS equipment, abnormal signals were found. The operation and maintenance personnel further located the fault by combining the ultrasonic method, and finally determined that the fault was floating discharge in the bus barrel caused by the loose shield. Timely treatment avoided insulation breakdown and reduced economic losses by more than 10 million yuan. Similarly, by detecting the concentration of SF6 decomposition products, potential faults in transformers, cables, and other equipment can be found in advance, ensuring the safe and stable operation of the power grid.
In addition, this standard also provides a basis for the procurement and inspection of SF6 decomposition products detectors in power enterprises, helping enterprises select high-quality detection instruments, improving the level of power equipment condition-based maintenance, reducing maintenance costs, and improving the reliability of power supply.
Q-GDW 11304.13-2015, as a key technical specification for SF6 decomposition products detectors, has established a complete set of standardized requirements for the design, production, and use of such instruments. Its implementation is conducive to improving the quality and detection accuracy of SF6 decomposition products detectors, strengthening the level of power equipment condition monitoring, and ensuring the safe and stable operation of the power grid. In the future, with the continuous innovation and development of power detection technology, it is necessary to further optimize and improve the relevant standards to adapt to the new needs of power grid development, providing stronger technical support for the high-quality development of the power industry.