用四单元电容传感器测量绝缘纸板微水分分布

Measurement of moisture distribution in pressboard using four-cell capacitive sensor

由于变压器绝缘纸板中的微水分影响其介电特性,用介电方法可以测量绝缘纸板微水分分布.测量系统采用一种有4个感应深度不等的测量单元的电容式传感器,轮流使用各测量单元可获得绝缘纸板的对应导纳,再利用绝缘纸板截面上分布测点的等效导纳,推导出绝缘纸板不同深度层上的介电特性,通过适当标定后,该测量系统可以用于估算被测绝缘纸板某深度的含水质量分数.试验证明了其使用效果.介绍了传感器的原理、结构及测量系统的构成.

The dielectrometry method can be used to measure moisture dynamics in transformer pressboard since the moisture affects the dielectric properties of pressboard. The capacitive sensor of the measuring system has four measuring cells with different detecting extent. By using each cell in turn, each corresponding complex admittance can be obtained and the dielectric properties of pressboard in different layers derived from the equivalent admittances array on pressboard profile. After calibration, the moisture content in different depths of pressboard can be estimated indirectly, which has been proved with experiments and simulation. The principle and structure of the sensor as well as the measuring systems are explained.