How to detect oil leakage in current transformer?
Jul 16, 2025| 1. Appearance inspection
Check the oil level: Check the oil level of the current transformer regularly to ensure that it is within the normal range. A low oil level may indicate an oil leakage.
Check for leakage: Observe whether there is oil leakage in the housing, seals and connection parts of the current transformer.
2. Image analysis method
Image acquisition: Use a camera, video camera or webcam to obtain an image sequence of the pole where the current transformer is located.
Foreground target detection: Use a foreground moving target detection algorithm (such as the Vibe algorithm) to process the image sequence and detect foreground moving targets.
Candidate area determination: Exclude foreground moving targets with shrinking areas and upward contour growth to determine candidate areas.
Double Gaussian model fitting: Perform double Gaussian model fitting on the candidate area, and determine whether there is an oil leakage based on the fitting results.
3. Infrared thermal imager detection
Temperature gradient detection: Use an infrared thermal imager to detect the temperature distribution on the outer surface of the current transformer. Oil level changes will produce a significant temperature gradient on the outer surface of the equipment, thereby determining whether there is an oil leakage.
4. Oil quality inspection
Regular sampling: For oil-filled current transformers, regularly sample and test the oil quality to evaluate its insulation performance and aging degree.
Check oil quality: Check the oil moisture content, breakdown voltage, tanδ (oil), chromatographic analysis (detection of fault gases such as H₂, CH₄).
5. Seal inspection
Check seals: Check whether the seals of the current transformer are damaged or aged.
Check bellows expander: For oil-immersed current transformers, check whether there is oil leakage at the top of the bellows expander.
6. Insulation test
Insulation resistance measurement: Regularly measure insulation resistance to evaluate the insulation condition of the transformer.
Withstand voltage test: Perform power frequency withstand voltage or induction withstand voltage test on the current transformer to verify its insulation performance.
7. Partial discharge test
Partial discharge detection: Perform partial discharge test when necessary to detect whether there is partial discharge phenomenon, which may be an early warning signal of reduced insulation performance due to oil leakage.
