GB/T 37141.2-2018 in English

Interpretation of the UV imaging inspection standard for power transmission lines in high altitude areas

1. Overview of the standard

GB/T 37141.2-2018 National Standard of the People's Republic of China "Guidelines for UV imaging inspection of electrical equipment in high altitude areas Part 2: Power transmission lines" specifies the methods and requirements for the use of UV imaging technology to inspect power transmission lines in high altitude areas. This standard is mainly applicable to AC transmission lines in areas with an altitude of $1~000~\mathrm{m} \sim 5~000~\mathrm{m}$, and also provides a reference for DC transmission lines.

2. Background of standard formulation

Due to the special geographical environment and climatic conditions (such as low pressure, low temperature, etc.) in high altitude areas, electrical equipment is easily affected by corona discharge and arc discharge. These discharge signals can be detected by UV imaging technology. This standard is formulated based on the research results of discharge UV detection in actual transmission lines and laboratories by relevant units, and aims to provide a scientific basis for the safe operation of transmission lines in high-altitude areas.

3. Comparison of standard frameworks

4. Testing conditions and instrument requirements

According to Chapter 4 of the standard, the test must meet the following conditions:

• Environmental conditions: Wind speed is less than $5~\mathrm{m/s}$, and the temperature range is $-30^{\circ}\mathrm{C} \sim +45^{\circ}\mathrm{C}$.
• Instrument requirements: Ultraviolet imaging equipment must meet the requirements of Appendix A, including photon counting function and high resolution.

5. Testing methods and technical points

The standard specifies two testing methods: general testing and fixed-point testing. General detection is used for qualitative analysis, while fixed-point detection is used for quantitative analysis:

• General detection: Use ultraviolet imaging equipment to scan the transmission line to determine the discharge equipment and location.
• Fixed-point detection: After determining the discharge equipment, record the average number of photons, detection distance and other parameters, and correct the number of ultraviolet photons to the standard distance (such as $10~\mathrm{m}$) through the formula.

6. Discharge type and defect treatment

According to Appendix E, the discharge type is divided into three forms: corona discharge, brush discharge and arc discharge. Defect treatment is divided into three categories according to severity:

• Category I: Record and observe, pay attention to development.
• Category II: Shorten the detection cycle and arrange maintenance.
• Category III: Handle as soon as possible.

7. Altitude correction of UV photon number

In order to adapt to the high altitude environment, the standard stipulates the altitude correction method of UV photon number (such as the formula $y_{0} = y \times \left(1 - \frac{H-1}{45.1}\right)^{5.36m}$) to ensure the accuracy of the test results.

8. Implementation suggestions

In order to effectively implement this standard, it is recommended to:

• Select UV imaging equipment that meets the requirements.
• Develop a reasonable test cycle based on the importance of the line and environmental conditions.
• Strengthen the recording and analysis of test data to ensure the integrity of the data.

9. Data management and reporting specifications

The standard requires detailed archiving of test records and reports. The report should include equipment model, test environment conditions, line name, defect analysis and treatment opinions, etc.