Failure Analysis Of Epoxy Resin Casing

3.1 Analysis of the main causes of common faults of epoxy bushing
Through the analysis of common faults of epoxy resin bushing, it is not difficult to find that there are four possible main causes of epoxy resin cast bushing defects: First, due to the incomplete vacuuming of epoxy bushing manufacturer during factory delivery or overhaul, air remains between the epoxy bushing for transformer screens, resulting in partial discharge and insulation breakdown; second, due to the poor quality of the rubber pad or the aging of the rubber pad due to super-cycle operation, the sealing failure may occur. If the top of the capacitor bushing is poorly sealed, it may cause insulation breakdown after water ingress. If the lower rubber pad is poorly sealed, the bushing will leak oil, causing the bushing insulating oil level to drop; third, due to long-term disrepair, the insulation performance of the bushing is reduced, and the porcelain is damaged or even broken down. After the dirt on the surface of the bushing absorbs moisture, the conductivity will increase, which will lead to a decrease in insulation resistance. Not only is it easy to cause surface flashover, causing tripping, but also due to the increase of leakage current, the insulating bushing will heat up, causing porcelain damage or even breakdown. At the same time, flashover will also damage the surface of the bushing; fourth, due to improper installation method or angle, the transformer will be defective.