Diagnosis method of internal defect of oil-immersed transformer

1. Defect characteristic gas content (analytical data) is measured and compared to the note value of dissolved gas content in the oil. If the gas concentration reaches the concern value (150ppm for total hydrocarbons and hydrogen compounds, and 5ppm for acetylene), further attention needs to be paid to microanalysis to find out the influencing factors.

2. Oil has the influence of gas volume, oil-immersed transformer capacity, operation mode, operation cycle and other related factors, so the attention value has a certain reference value in reflecting the probability of defect occurrence. Only the analysis effect of attention value is difficult to accurately diagnose the severity of oil-immersed transformer defects. On this basis, the influence of gas recovery rate, etc. is fully considered, and the diagnosed oil-immersed transformer and the detected characteristic gas are distinguished from the bias voltage. In this way, it is possible to judge whether the oil-immersed transformer is defective according to the analysis, and to preliminarily infer the nature of the defect. The gas production is directly related to the defect energy, defect location and defect temperature. By measuring the incidence of defective gases, the internal state of oil-immersed transformers can be further diagnosed.

3. To clarify the real factors of gas attack, in order to prevent errors caused by non-defective factors, when diagnosing the defects of oil-immersed transformers, it is necessary to fully understand the structure, manufacture, equipment and operation, inspection, and auxiliary equipment of oil-immersed transformers that have been confirmed. The chromatographic analysis data is contacted for comprehensive analysis, and it is confirmed whether the oil-immersed transformer is defective.