Mitigating Partial Discharge Defects in Transformer Manufacturing
The direct cause of partial discharge phenomena in power transformers is the non-uniformity of electric field strength. By ensuring proper oversight during the manufacturing process regarding the following two points, we can significantly reduce partial discharge defects in transformers:
Asymmetry of Equipment Electrodes
In cases of pointed or cylindrical bodies, such as transformer bushing terminals or the connections within the transformer, poor contact can lead to concentrated electric fields in these areas. Without effective measures or with poor manufacturing quality, this can easily result in tip or surface discharges.
Non-Uniformity of Insulating Medium
In the internal manufacturing process of transformers, various solid media, in addition to insulating oil, are used, such as resin, plastic, mica, and fiber products. Since the dielectric constant of gas is low compared to liquids and solids, the presence of bubbles in oil or voids in solid insulating materials during manufacturing can lead to higher electric field strength in the alternating field, but with much lower voltage resistance—only a fraction of that of solid and liquid media. Consequently, discharges often initiate in these voids. If the oil is improperly treated, bubbles can form, or aging of insulating materials during operation can also lead to bubble formation, significantly lowering the initial voltage required for partial discharge. Additionally, if the oil contains impurities or has a high moisture content, the maximum electric field strength can increase threefold, causing discharges to occur at lower testing voltages.
In conclusion, addressing the factors contributing to partial discharge in power transformers is crucial for enhancing their reliability and longevity. By focusing on the symmetry of equipment electrodes and ensuring the uniformity of insulating media during manufacturing, we can significantly mitigate the risk of partial discharge. Proper treatment of insulating oil and monitoring for impurities and moisture content are essential practices that will help maintain optimal performance. Ultimately, a proactive approach in the manufacturing process not only reduces the likelihood of partial discharges but also ensures the overall efficiency and safety of power transformer operations.
