This paper deals with partial discharge characteristics in oil/pressboard composite insulation system, which is used in oil-immersed power transformer. It is found that the discharge propagates in the same route on the pressboard surface as in the previous discharge every time under repeated impulse voltage application. We also revealed that the white trace remained along the path of discharge and affected the subsequent discharge progress because of being a weak point part on insulation. This study presents an investigation of the effect of the white trace on partial discharge inception voltage (PDIV) of the composite insulation system with high-speed optical observation and electrical measurements for the discharge propagation. The discharge propagation mechanism is also discussed with comparing the discharge progress characteristics before and after the white trace formation.

中文翻译：

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油/纸板复合绝缘中的蠕变放电特性

本文探讨了油浸式电力变压器油/压板复合绝缘系统的局部放电特性。可以发现，在反复施加脉冲电压的情况下，放电每次都在压板表面上以与先前放电相同的方式传播。我们还发现白色痕迹沿放电路径保留，并由于绝缘的薄弱部分而影响了随后的放电进度。本研究通过高速光学观察和电学测量放电传播，研究了白色迹线对复合绝缘系统的部分放电起始电压（PDIV）的影响。