利用SiC电致发光特性在线测量防晕层表面电场分布

Online Measurement of Surface Electric Field Distribution of SiC Stress-Grading Coating Based on Electroluminescence

基于SiC材料电致发光强度随电场强度增大而增强的特性,提出了一种在线测量发电机定子线圈端部SiC防晕涂层表面电场分布的新方法.该方法利用绝缘塑料光纤作为受光探头,避免了探头接触防晕涂层表面时引起该处电场畸变的问题.测量装置主要由光电转换、信号放大、信号处理单元组成.SiC防晕涂层特定点处电致发光信号波的峰-峰值Vp-p与该处电场强度E之间呈对数关系.将此测量方法用于1级和3级SiC防晕涂层,实际测量所得防晕涂层各点的电场强度值与理论计算值符合较好,误差均能控制在0.05以内,说明该方法准确度较高.

The property that SiC electroluminescent intensity is enhanced with an increase of electric field motivates to propose a novel method for online detection of surface electric field distribution in the SiC stress-grading coating. The electric field distortion on the measurement spots is minimized by the insulated plastic optical fibre as the probe collects the electroluminescence of the SiC stress-grading coating. The self-designed measuring system primarily contains opticalelectrical converter, signal amplifier and signal processing unit. The relation between the peakpeak values of the electroluminescence signal and the electric field of special spots of the stressgrading coating follows the logarithm law. When the method is applied to one and three orders SiC stress-grading coating, the measured values agree well with the calculated ones on the various spots, indicating the accuracy and reliability of this method.