This paper presents an experimental study of the fundamental phenomena of progressive creeping discharge as well as the influences of pressboard ageing and voltage amplitude under divergent AC voltages. A ramp-stress test is used to determine the partial discharge inception voltage (PDIV) and the flashover voltage of oil/pressboard interface versus pressboard ageing. Constant-stress tests are carried out to investigate the partial discharge (PD) behaviors, the pressboard surface temperature, and the oil-dissolved gases of progressive creeping discharges. It is found that the pressboard ageing affects only the interface PDIV. The progressive creeping discharges concentrate at the triple-junction and comprises probably oil corona discharges and surface discharges in pressboard dimples. If no pressboard damage is present, the progressive discharges exhibit in general a constant PD pattern but a diminishing intensity, and nevertheless can be sustained for the severely-aged pressboards under strong voltages. The underlying causes are correlated with the competing effects of pressboard ageing on interface moisture and the triple-junction field intensification. Gas analyses indicate the hydrogen is the principal faulty gas and the Duval's Triangle diagnoses the progressive creeping discharges as either low-energy or high-energy discharge fault. No pressboard overheating is observed during the discharges.

中文翻译：

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发散交流电压下的油/纸板沿面放电研究——图1：基本现象和影响因素


本文对渐进沿面放电的基本现象以及不同交流电压下纸板老化和电压幅值的影响进行了实验研究。斜坡应力测试用于确定油/纸板界面的局部放电起始电压 (PDIV) 和闪络电压与纸板老化的关系。进行恒应力测试以研究局部放电 (PD) 行为、纸板表面温度以及渐进蠕变放电的油溶气体。发现纸板老化仅影响PDIV接口。渐进的沿面放电集中在三联结处，并且可能包括油电晕放电和纸板凹坑中的表面放电。如果不存在纸板损坏，则渐进放电通常表现出恒定的局部放电模式，但强度逐渐减弱，但对于严重老化的纸板来说，在强电压下仍然可以维持。根本原因与纸板老化对界面湿度和三结场增强的竞争影响有关。气体分析表明氢气是主要的故障气体，杜瓦尔三角将渐进式蠕变放电诊断为低能量或高能量放电故障。在放电期间没有观察到压板过热。