Abstract: Q-GDW-11304.3-2019 is an important enterprise standard formulated by State Grid Corporation of China, which specifies the technical requirements, test methods and inspection rules for ultraviolet imagers used in live detection of power equipment. As a key part of the “Technical Specifications for Live Detection Instruments of Power Equipment” series standards, this standard plays a crucial role in standardizing the performance indicators, ensuring the detection accuracy and promoting the safe and stable operation of power grids. This article conducts an in-depth analysis of the core content of Q-GDW-11304.3-2019, focusing on technical requirements, test items and industrial application value, to provide technical reference for relevant practitioners in the power industry.

Keywords: Q-GDW-11304.3-2019; ultraviolet imager; live detection; power equipment; technical specification

1. Introduction

With the continuous expansion of the scale of power grids and the increasing demand for reliable power supply, live detection technology of power equipment has become an important means to ensure the safe operation of power systems. Ultraviolet imagers, as core equipment for detecting partial discharge of external insulation of power equipment, can realize non-contact detection of discharge defects without changing the operation state of main equipment, which is of great significance for early warning of equipment faults and reducing unplanned power outages. Q-GDW-11304.3-2019, as the special technical specification for ultraviolet imagers, defines the technical requirements and test standards for such equipment, filling the gap in the standardization of ultraviolet imaging detection equipment in the domestic power industry and laying a solid foundation for the standardized application of ultraviolet detection technology.

The “Technical Specifications for Live Detection Instruments of Power Equipment” series standards include 21 parts, among which Q-GDW-11304.3-2019 is the third part, specifically targeting ultraviolet imagers. This standard is formulated on the basis of summarizing the practical experience of live detection of power equipment and absorbing advanced domestic and foreign technical achievements, which is compatible with relevant national standards such as GB 4793.1-2007 and GB/T 6587-2012, and has strong practicality and operability.

2. Core Technical Requirements of Q-GDW-11304.3-2019

Q-GDW-11304.3-2019 specifies detailed technical requirements for ultraviolet imagers from two aspects: basic functions and performance indicators, covering the key technical parameters that affect the detection effect and operation safety of the equipment.

2.1 Basic Function Requirements

According to the standard, ultraviolet imagers must have basic functions such as data query, storage and export to ensure that the detection data can be effectively recorded and traced. At the same time, the equipment should be equipped with alarm threshold setting and indication functions to timely prompt operators of abnormal discharge signals. In view of the complex electromagnetic environment of power equipment operation, the instrument should have interference suppression capability to avoid false detection caused by external electromagnetic interference. For battery-powered ultraviolet imagers, the battery should be easy to replace, and the continuous working time should not be less than 4 hours to meet the needs of long-term on-site detection.

In terms of professional functions, the standard emphasizes that ultraviolet imagers should realize the separate imaging and superposition display of ultraviolet light and visible light, and the superposition accuracy should not exceed 1 mrad. The instrument should have good solar-blind characteristics, which can effectively shield the interference of solar ultraviolet rays and ensure the detection effect under daytime conditions. In addition, the equipment should be equipped with functions such as ultraviolet photon counting, gain adjustment, ultraviolet denoising and threshold filtering, which can accurately count the ultraviolet photons in the specified area and improve the accuracy of discharge defect identification.

2.2 Key Performance Indicators

The performance indicators specified in Q-GDW-11304.3-2019 are the core basis for evaluating the quality of ultraviolet imagers, mainly including the following aspects:

Wavelength range: The ultraviolet channel of the instrument should work in the solar-blind ultraviolet band, with a wavelength range of 240-280 nm, which can avoid the interference of natural light and improve the specificity of discharge detection.

Sensitivity: The minimum ultraviolet light sensitivity should not be greater than 3×10⁻¹⁸ W/cm², and the minimum discharge sensitivity should not be greater than 5 pC at a detection distance of 10 m. High sensitivity ensures that the instrument can detect weak discharge signals, which is crucial for early detection of equipment defects.

Imaging quality: The ultraviolet imaging angular resolution should not be greater than 5 mrad, and the number of lines per image height should be not less than 15 lines/image height. The visible light resolution should be at least 768×576 pixels, and the minimum visible light sensitivity should not be greater than 0.1 Lux, which can ensure clear imaging of discharge points and their surrounding environments, facilitating operators to accurately locate defects.

Environmental adaptability: The instrument should be able to withstand the temperature test of group Ⅲ specified in GB/T 6587-2012 and the humidity test of group Ⅲ, and the shell protection level should not be lower than IP31 in accordance with the requirements of GB 4208. This ensures that the equipment can work stably in harsh on-site environments such as high temperature, high humidity and dust.

3. Test Requirements and Methods

To ensure that ultraviolet imagers meet the technical requirements specified in the standard, Q-GDW-11304.3-2019 stipulates a complete set of test items and corresponding test methods, which mainly include type tests and routine tests. The type test is carried out when the product is developed or modified, and the routine test is carried out for each product leaving the factory.

3.1 Safety Tests

Safety is the primary requirement for live detection equipment. The standard requires that ultraviolet imagers must meet the safety requirements of GB 4793.1-2007. For instruments with a power supply voltage exceeding 30 V AC (effective value) or 60 V DC, the contact current between the shell and the ground should not be greater than 3.5 mA effective value (sine wave). The instrument should withstand a dielectric strength test for 1 minute, and the test voltage should be selected according to the rated working voltage. For example, the test voltage between the power circuit and the case of battery-powered instruments is 500 V AC effective value. No breakdown or repeated arcing is allowed during the test, but corona effect and similar phenomena are permitted.

3.2 Performance Tests

Performance tests cover key indicators such as sensitivity, imaging quality and function. The ultraviolet light sensitivity test is carried out by using a standard ultraviolet light source to measure the minimum ultraviolet light intensity that the instrument can detect. The discharge sensitivity test is completed by using a partial discharge generator to simulate different levels of discharge signals and verifying the instrument’s detection capability. The imaging quality test includes measuring parameters such as angular resolution, line number per image height and superposition accuracy to ensure that the imaging effect meets the standard requirements.

3.3 Environmental Adaptability Tests

The temperature test is carried out in a high and low temperature test chamber, and the instrument is placed in a specified temperature environment for a certain period of time, then its performance indicators are measured to verify its temperature adaptability. The humidity test is carried out in a constant temperature and humidity test chamber, and the instrument is placed in a high humidity environment for a specified time to check its working stability. In addition, the instrument also needs to pass vibration tests, impact tests and transportation tests to ensure that its performance is not affected during transportation and on-site use.

3.4 Electromagnetic Compatibility Tests

Considering the complex electromagnetic environment of power grids, the standard requires ultraviolet imagers to pass a series of electromagnetic compatibility tests, including electrostatic discharge immunity test, radio frequency electromagnetic field radiation immunity test, electrical fast transient pulse group immunity test, surge (impact) immunity test, etc.. These tests ensure that the instrument can work normally without being disturbed by external electromagnetic fields, and will not interfere with the quality of power communication during operation.

4. Industrial Application Value and Significance

The formulation and implementation of Q-GDW-11304.3-2019 have important guiding significance for the application of ultraviolet imaging technology in the power industry and the healthy development of the related equipment manufacturing industry.

For the power operation and maintenance department, the standard provides a unified technical basis for the selection, use and inspection of ultraviolet imagers. Standardized equipment ensures the accuracy and reliability of live detection data, helps operators to accurately evaluate the operation state of power equipment, early warn potential defects, and improve the efficiency of equipment maintenance. For example, in the inspection of power transmission lines and substations, ultraviolet imagers that meet the standard can effectively detect discharge defects such as insulators, busbars and switchgear, and provide a reliable basis for maintenance decisions.

For equipment manufacturers, the standard clarifies the technical requirements and test standards for ultraviolet imagers, which guides the research and development and production of products. Manufacturers can carry out product design and optimization according to the standard requirements, improve product quality and market competitiveness. At present, many domestic manufacturers have developed ultraviolet imagers that meet the requirements of Q-GDW-11304.3-2019, which can pass the type test of China Electric Power Research Institute and are widely used in power grid inspection work, including being equipped on inspection UAVs or inspection robots to realize intelligent detection.

In addition, the standard also promotes the standardization and normalization of live detection technology of power equipment in China, and provides technical support for the construction of smart grids. By standardizing the performance and test of ultraviolet imagers, the consistency and comparability of detection data are improved, which is conducive to the integration of detection data into the smart grid operation and maintenance management system and realizes the refined management of power equipment.

Q-GDW-11304.3-2019, as a special technical specification for ultraviolet imagers in live detection of power equipment, has important practical significance for standardizing the technical indicators of ultraviolet imagers, ensuring the safety and reliability of live detection work and promoting the stable operation of power grids. The standard comprehensively covers basic functions, performance indicators, test methods and other aspects, with strong operability and guiding value. With the continuous advancement of smart grid construction, the application of ultraviolet imaging technology will become more and more extensive. In the future, it is necessary to further improve and optimize the standard according to the development of technology and the needs of practical application, so as to better serve the high-quality development of the power industry.