Influence of Typical Defects on Insulation and Gas Production Characteristics of Oil-Impregnated Paper Bushing

Potential defects in oil-impregnated paper (OIP) bushing during manufacturing or transportation may further deteriorate and develop under long-term operation, affecting the insulation, and leading to transformer damage and power outage. In this article, scaled models are designed and produced according to 550 kV OIP bushing, and typical defects, including the plate wrinkle defect, the plate deviation defect, the plate damage defect, the moisture defect, and the end shield ungrounded defect are set in the models. Based on a long-term high-voltage experiment platform, a 45-day simulated operation is applied to the defect models, as well as the nondefect one. The tests of partial discharge (PD), frequency domain dielectric response, and dissolved gas in oil are carried out every few days. The results indicate the models with the plate wrinkle defect and the moisture defect have the most significant changes, with enhancing PD, increasing dielectric loss, and growing dissolved gas in the oil. The capacitance of the end shield ungrounded defect model is much different, which can be quickly recognized. The results of others have not changed much, perhaps due to the absence of discharge during long-term experiments. In addition, the combination of three tests can provide more valuable references.