油纸绝缘电导特性实时测试系统及方法

Real Time Test System and Method of Conduction Characteristics of Oil-paper Insulation

换流变压器阀侧绕组绝缘设计需考虑油纸绝缘电导特性的影响，而现有电导率测试方法均存在无法真实模拟直流电场应力的问题。为此，建立并提出了油纸绝缘电导特性实时测试系统及方法，试验研究了长度为8narn的油隙及厚度为6mm的油浸纸板的体积电导率在不同电场强度（简称场强）、不同温度下的电导特性。结果表明：建立的测试系统可直接测量油纸绝缘体积电导率，可用于进行均匀电场下电导特性的研究；被测8mm油隙体积电导率在场强S3kV／mm时呈现明显的温度效应，场强〉3kV／mm时呈现明显的场强效应；被测6mnl油浸纸板的体积电导率相对稳定，处于10^-16~10^-17S／m范围内。所得试验结果可用于优化换流变阀侧绕组的绝缘设计。

It is necessary to consider the conduction characteristics of oil-paper insulation when designing valve windings of converter transformers. However, current test methods of conductivity cannot simulate DC electrical stress directly. Therefore, we proposed a real-time test system and a method for testing conduction characteristics of oil-paper insulation, and used them to test the conductivity of a 8 mm-long transformer oil gap and a 6 mm-thick impregnated pressboard, re- spectively, under different field intensities and temperatures. The test results show that the proposed system can measure volume conductivity of oil-paper insulation directly, so it can be applied to study conduction characteristics in uniform electrical field. The volume conductivity of the 8mm oil gap presents an obvious temperature effect when the electrical field intensity is less than 3 kV/mm, but it presents an obvious field effect when the electrical field is more than 3 kV/mm. The volume conductivity of the impregnated pressboard is stable and within the range of 10^-16--10^-17 S/m. These test results can be used to optimize the valve-side insulation design of convertor transformers.