DL/T 1986-2019 in English

This standard establishes for the first time the detection technology system for sulfur hexafluoride mixed gas insulation equipment, and standardizes the technical requirements for 10 major categories of detection items for mixed gases such as SF₆/CF₄ and SF₆/N₂.

1. Infrared imaging leak detection technology: For the first time, the technical requirement of NETD (noise equivalent temperature difference) ≤ 0.05K is clarified, and the visual detection of SF₆ leaks with a 10-second response is realized.

2. Dual sensor combination: The mixed gas ratio detection uses a thermal conductivity/infrared sensor and an electrochemical oxygen sensor to work together to ensure that the SF₆ detection error is ≤ 1% and the O₂ detection error is ≤ 0.1%.

Case 1: Abnormal gas mixture ratio of GIS equipment
A 500kV substation uses SF₆/N₂(30/70) mixed gas. Gas chromatography detection found that the N₂ content deviation reached 3.2%. After investigation, it was found that the charging ratio control valve was faulty.

Case 2: Decomposition product warning
The DL/T 1205 method detected that the SO₂+H₂S content exceeded the limit value (2μL/L), and the internal arc discharge defect of the circuit breaker was discovered in time.

1. Testing equipment selection: Prioritize multi-parameter detectors that meet the requirements of Article 6.1.1.2 of the standard, which must have annual calibration functions.

2. Tail gas treatment: Strictly implement the requirements of Article 7.5, and use alkaline solution absorption or special recovery equipment to treat the test tail gas.

3. Data recording: The test report should contain 9 core contents as required by Chapter 8, especially environmental parameters and instrument calibration information.