GB/T 42287-2022 in English
VALIDHigh-voltage test techniques—Measurement of partial discharges by electromagnetic and acoustic methods
- Issued on:2022-12-30
- Implemented on:2023-07-01
- File Format:PDF
- Delivery:Via email within 5 business days
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《GB/T 42287-2022高电压试验技术 电磁和声学法测量局部放电》由TC163（全国高电压试验技术和绝缘配合标准化技术委员会）归口，主管部门为中国电器工业协会。
Introduction
Analysis of the core content of the standard
GB/T42287-2022 is equivalent to IECTS62478:2016, which establishes the electromagnetic and acoustic measurement methodology for partial discharge of high-voltage equipment. The standard is applicable to the insulation status assessment of equipment such as GIS, transformers, and rotating motors.
Electromagnetic Measurement Technology System
| Frequency band | Sensor type | Typical application | Sensitivity(pC) |
|---|---|---|---|
| HF(3-30MHz) | Capacitor/Current Transformer | Cable accessories | ≥5 |
| VHF(30-300MHz) | Rogowski coil | Stator winding | ≥10 |
| UHF(300MHz-3GHz) | Conical sensor | GIS/Transformer | ≥5 |
Key technical points of electromagnetic method:
- Propagation characteristics: The propagation speed of UHF waves in oil is about 2×108m/s (εr dependent)
- Sensitivity verification requires the correlation between pC and measured values through IEC60270 comparative experiments
- Typical signal attenuation in GIS: 2dB/m in straight pipe section, 1-5dB in interval air chamber
Acoustic Measurement Implementation Specifications
The acoustic method adopts the 20kHz-250kHz ultrasonic frequency band. The main sensor types are:
- Piezoelectric accelerometer: flat frequency response, output is proportional to acceleration
- Acoustic emission sensor: resonant response, output is proportional to speed
Typical installation requirements:
- At least one measuring point for each air chamber of the GIS casing, avoiding the insulator flange
- A safe distance must be maintained on the top of the transformer oil tank, avoiding the reinforcement ribs
Combined positioning technology
The implementation principle of the acoustic-electromagnetic combined positioning method recommended by the standard:
Positioning error = |(tacoustic-tUHF)×voil| Wherein the speed of sound in oil voil≈1300m/s(50℃)
The application case in the transformer shows that this method can improve the positioning accuracy to ±30cm.
Recommendations for the implementation of the standard
- Newly built GIS should be pre-installed with UHF couplers, with a spacing of ≤20m
- Reinstalling the acoustic sensor after it has been fixed will result in a sensitivity deviation of approximately 3dB
- Distributed capacitive sensor systems should be used preferentially for cable accessory detection
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