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通过对水轮发电机定子线棒主绝缘中气隙群放电的理论计算和交流工频I～U曲线的第一电流急增点的测量分析,研究了相同电压等级(15.75kV)的多胶模压和少胶VPI线棒的气隙群特征及冷热循环对气隙群放电的影响。结果表明,15.75kV的多胶模压和少胶VPI线棒的气隙群特征相近;冷热循环使气隙群的等效间距由10μm以下变为50μm以上,气隙群放电时试品的电容变化值由40pF以下增加至110pF以上,同时电容变化计算值与常态介损增量的测量值随循环次数的变化规律具有较好的一致性。
Through the theoretical calculation of the air gap group discharge in the main insulation of the stator of the hydroelectric generator and the measurement and analysis of the sharp increase of the first current in the AC power frequency I ~ U curve, the same voltage level (15.75kV) Characteristics of Air Gap Groups with Molded and Less Plastic VPI Bar and Effects of Cooling and Heating Cycles on Air Gap Group Discharge. The results show that the air gap group characteristics of 15.75kV multi-plastic molded and less plastic VPI bar are similar; the equivalent spacing of air gap group is changed from below 10μm to above 50μm by hot and cold cycles; the capacitance The change value increases from below 40pF to above 110pF. At the same time, the calculated value of capacitance change and the change of normalized dielectric loss increment with the number of cycles have good consistency.