GOALI: Optical Tomography Measurements of High Voltage Conduction and Breakdown Phenomena in Dielectrics

9820515Zahlovan提出的研究是一个GOALI工业大学合作项目之间的麻省理工学院和EPRI的持续分析，计算，和实验研究使用光学断层扫描测量高压绝缘，传导，预击穿和击穿特性绝缘体。 该方法使用电场诱导的双折射（克尔效应）与改进的灵敏的光学测量系统和新的先进的数学公式，允许计算电场的大小和方向在任何电极的几何形状从opticalintensity测量。 由于大多数金属/电介质系统的高压电荷注入和传输、预击穿和电击穿的物理特性都是未知的，因此不能仅从系统几何形状的知识来计算电场分布。 光学测量提供了一种直接的方法来确定电本构关系和学习电击穿过程的物理过程，因此提供了一种研究方法，在提高介电系统的击穿强度的重大进展。拟议的继续研究计划涉及研究生和本科生与EPRI人员一起，试图进一步了解电荷注入，传导，老化，退化，预击穿和击穿机制，在高场强调气体，液体和固体使用新的现代光学，电子，and computer计算机instrumentation仪器to give "eyes眼睛"在材料内部观察预击穿和击穿场以及以前无法测量的电荷分布。具体建议的工作任务是：扩展和完善了克尔效应的理论公式，其中，对于任意三维几何形状，外加电场的大小和方向沿光路沿着变化;开发了将测量的光信号转换为电场分布的计算算法;并用实验验证了分析; 2）开发一种计算机接口的摄像系统，该系统具有分布在一个区域上的光学阵列探测器，以在没有机械运动的情况下自动获取和处理敏感的克尔测量数据; 3）在良好控制和监控的测试单元中对各种液体/液体进行灵敏的克尔电光场和电荷映射测量。- 体积中和界面附近的电双层内的固体材料组合作为DC电压幅度和极性、AC电压幅度和频率的函数，4）扩展了Kerreffect技术的灵敏度，并对脉冲、斜坡和其它时变电场中的弱介电常数进行了测量; 5）将建模、光学测量和介电测量的结果与更好地理解高压传导联系起来，预击穿和击穿现象，以便可靠地将高压设备的操作扩展到更高的电压;和6）构建一个紧凑的光学传感器测量系统，在EPRI人员和承包商的帮助下，该系统将应用于运行中的Transformer中的电场和空间电荷测量。

9820515ZahnThe proposed research is a GOALI industry-university collaborative projectbetween MIT and EPRI for the continued analytical, computational, andexperimental study using optical tomography measurements of high voltageinsulation, conduction, prebreakdown and breakdown characteristics indielectrics. The methodology uses electric field induced birefringence(Kerr effect) with an improved sensitive optical measurement system and anew advanced mathematical formulation that allows calculation of electricfield magnitude and direction in any electrode geometry from opticalintensity measurements. Because the physics of high voltage chargeinjection and transport, prebreakdown and electrical breakdown are not knownfor most metal/dielectric systems, the electric field distribution cannot becalculated from knowledge of system geometries alone. Optical measurementsprovide a direct approach to determining electrical constitutive laws andlearning the physics of the electrical breakdown process and so offers aresearch methodology for major advances in increasing the breakdown strengthof dielectric systems. The proposed continuing research program involves both graduate andundergraduate students together with EPRI personnel to try to furtherunderstand charge injection, conduction, aging, degradation, prebreakdownand breakdown mechanisms in high field stressed gaseous, liquid, and soliddielectrics using new modern optical, electronic, and computerinstrumentation to give "eyes" inside materials to see prebreakdown andbreakdown field and charge distributions that could not be measured before.Specific proposed work tasks are 1) Extend and complete the mathematicalformulation of the Kerr effect where the applied electric field magnitudeand direction change along the light path for any three dimensionalgeometry; develop computational algorithms to convert measured opticalsignals to electric field distributions; and to verify analysis withexperiments; 2) Develop a computer interfaced camera system with an opticalarray detector distributed over an area to automate sensitive Kerrmeasurement data acquisition and processing without mechanical motion; 3)Perform sensitive Kerr electro-optic field and charge mapping measurementsin a well controlled and monitored test cell for various liquid/solidmaterial combinations in the volume and within the electrical double layernear interfaces as a function of DC voltage amplitude and polarity, ACvoltage amplitude and frequency, direction of interface with respect toapplied electric field, temperature, moisture, conductivity, andconcentration of moisture and trace additives; 4) Extend the sensitive Kerreffect technique and perform measurements for weakly birefringentdielectrics in pulsed, ramped, and other time varying applied electricfields; 5) Relate the results of the modelling, optical measurements, anddielectrometry measurements to a better understanding of high voltageconduction, prebreakdown and breakdown phenomena in dielectrics in order toreliably extend the operation of high voltage apparatus to higher voltages;and 6) Construct a compact optical sensor measurement system that with thehelp of EPRI personnel and contractors will be applied to electric field andspace charge measurements in an operating transformer.***