Dielectrometry Sensors and Algorithms to Monitor Moisture Dynamics and Other Impurities in Transformers

小行星9523128 新的捕获传感器可以测量电导率和介电常数的分布在微波。 每个传感器都有一组叉指电极，它们以时间频率f和空间波长施加空间周期性电压源。 在空间中具有周期性的激发的情况下，场在垂直方向上以等于空间波长的穿透深度衰减。 一组电极用变频AC电压驱动，并且高阻抗测量是由在另一组浮动电极上的感应电压进行的。 浮动电压的大小和相位取决于与传感器相邻的介质的介电常数和电导率。 从作为不同波长传感器的频率的函数的这种增益/相位测量，计算机算法可以计算介电常数和电导率的空间分布。 通过校准介电常数和电导率对其他物理变量的依赖性，例如湿度、温度、可燃气体浓度、痕量杂质浓度等，不可能测量作为时间函数的这些物理量的空间分布。 最近EPRI资助的研究已经进行了初步的校准之间的水分和温度的电导率和介电常数，使传感器可以用来监测的时间和空间动态的水分浸油Transformer纸板。 拟议的研究是开发有效的计算机算法，可以提取变压器中的纸板水分作为时间和空间的函数，使这种趋势分析和先进的诊断由EPRI和几个电力公司赞助的监测系统。 其他研究任务建议扩展介电测量传感器的能力，包括对特殊封装涂层的研究，这些涂层选择性地吸收或反应变压器中的可燃气体和其他微量杂质，如抗氧化剂，拟议的抗静电添加剂，如苯并三唑（BZA），以及老化和腐蚀产生的其他杂质。 ***

9523128 Lesieutre New captive sensors can measure distributions of conductivity and permittivity in dielectrics. Each sensor has a set of interdigitated electrodes which impose a spatially periodic source of voltage at temporal frequency f and spatial wavelength. With an excitation that is periodic in space, the fields decay in the perpendicular direction with a penetration depth equal to the spatial wavelength. One set of electrodes are driven with a variable frequency AC voltage, and a high impedance measurement is made of the induced voltage on the alternate set of floating electrodes. The magnitude and phase of the floating voltage depends on the dielectric permittivity and electrical conductivity of the medium adjacent to the sensor. From such gain/phase measurements as a function of frequency for different wavelength sensors, computer algorithms can calculate spatial profiles of the permittivity and conductivity. With calibration of permittivity and conductivity dependence on other physical variables such as moisture, temperature, concentration of combustible gas, concentration of trace impurities, etc., it is impossible to measure spatial distributions of such physical quantities as a function of time. Recent EPRI funded research has performed the preliminary calibration between moisture and temperature to conductivity and permittivity so that the sensors can be used to monitor the time and space dynamics of moisture in oil impregnated transformer pressboard. The proposed research is to develop efficient computer algorithms that can extract the pressboard moisture as a function of time and space in transformers so that this monitoring system of trend analysis and advanced diagnostics sponsored by EPRI and several electric utilities. Other research tasks propose to extend the capability of the dielectrometry sensor to include the investigation of special encapsulating coatings that are selectively absorbing or reactive to combustible ga s and other trace impurities in transformers such as anti-oxidants, proposed anti-static additives such as benzontriazole (BZA), and other impurities resulting from aging and corrosion. ***