Trial Assemble of Pockels Potential Distribution Sensor by Applying Fiber Array Technique

为了设计设备和提高绝缘效率，需要关于发生局部放电的电气设备内部的电势和场分布的信息。本研究旨在开发一种新的绝缘平板二维电位分布传感系统。该系统由普克尔斯晶体、光学元件和阵列式光学元件组成，第一年研制了一种具有光传输功能的光纤探针。该传感器无需任何光学调整即可进行高压测量。通过对该电位探针空间分辨率的研究，证明了光纤阵列传感系统难以达到预期的空间分辨率。因此，本文对传感系统的设计进行了讨论和改进，并在第二年研制出改进后的系统。该系统由脉冲激光器、扩束器、PBS、BGO普克尔斯晶体和CCD摄像机组成。在不引起任何场干扰的情况下，可以测量绝缘板上的二维电势分布。该系统的最小分辨率可达0.2纳秒。用该系统测量了负沿面放电在大气中传播时电位分布的瞬态变化。沿面放电传播过程中，流注尖端附近电场E_x的传播分量超过30kV/cm。这些二维电位分布图将有助于更合理地建立流注模型进行电场计算，并有助于阐明沿面放电的传播过程。

Information on the potential and the field profile inside electrical apparatus in which partial discharges occur is required for designing apparatus and improvement of insulation efficiency. This research started to develop a new sensing system for two-dimensional potential distribution on an insulating plate. The system was planned to consist of Pockels crystal, optical components and arrayed optical fibres.A potential probe, which has a pair of optical fibres for light transmission, is developed in the first year. This sensor can apply the high voltage measurement without any optical adjustment. After the investigation of the space resolution of this potential probe, it is proved out to be difficult to achieve the intended space resolution with the sensing system with fibre-array method. So, the design of the sensing system is discussed and improved.In the second year, the improved system is developed. The system finally consists of a pulse laser, a beam expander, PBS, a BGO Pockels crystal and a CCD camera. The two-dimensional potential distribution on an insulating plate can be measured without causing any field disturbance. The minimum resolution of this system reaches up to 0.2 nano-second. The transient change of potential distribution with a propagating negative surface discharge in atmospheric air is measured with this system. The propagating component of the electric field E_x near the tip of the propagating streamer exceeds 30kV/cm.These two-dimensional potential distribution profiles are expected to be helpful to the electric field calculation with more adequate streamer model and clarifying the propagation process of surface discharge.