1. Judging aging through insulating oil testing

Conduct dissolved gas chromatography analysis, dielectric loss, breakdown voltage, moisture, and acid value testing on transformer oil. An abnormal increase in acetylene, hydrogen, and total hydrocarbon content in the oil indicates internal overheating or discharge; excessive acid value, increased dielectric loss, and decreased breakdown voltage indicate severe aging of the insulating oil, which will accelerate the deterioration of winding insulation. The degree of solid insulation aging can be directly determined by the furfural content in the oil, with higher furfural concentration indicating more severe paperboard aging.

2. Judging aging through winding insulation characteristic testing

Using an insulation resistance tester to measure insulation resistance, absorption ratio, and polarization index, if the values significantly decrease and decay rapidly over time, it indicates that the insulation is affected by moisture and aging. Using a dielectric loss tester to measure tanδ, if the dielectric loss increases significantly, it represents overall aging and deterioration of the insulation. Conducting a partial discharge test, if the discharge amount exceeds the standard, it reflects the presence of aging defects and weak spots in the insulation.

3. Judging aging through winding DC resistance

Test the DC resistance of each phase winding and the three-phase imbalance. If the resistance value increases, the three-phase difference becomes larger, or there is a significant deviation from historical data, it indicates that the winding has issues such as wire aging, joint oxidation, poor contact, and broken strands, which indirectly reflects the overall aging of the equipment.

4. Judging the aging of iron core and winding through no-load and load tests

The no-load test detects the no-load current and no-load loss. An increase in these values indicates issues such as core aging, deteriorated silicon steel sheet performance, and multiple grounding points. An increase in short-circuit impedance and load loss indicates aging of winding conductors, structural loosening, and thinner insulation. By comparing with historical data, the aging trend can be determined.

5. Visually judge aging through operating status and appearance

Observing the appearance of the transformer, we find severe corrosion and oil leakage in the oil tank, aging and cracking of the bushing, and hardening and failure of the sealing components, all of which are manifestations of aging. During operation, abnormal noise increase, increased vibration, and higher temperature rise indicate aging of the iron core, winding, and structural components. By considering the operating years, load history, and fault records, a comprehensive assessment of the overall aging level is made.