超声波技术在大电机绝缘检测中的应用研究

Study on the Application of Ultrasonic Technique to Stator Insulation Diagnosis

用研制的检测系统 ,对大电机定子线棒进行了绝缘超声波参数测量和绝缘缺陷的检测试验。结果表明 ,使用 0 5MHz、 0 8MHz和 1 2MHz的超声换能器 ,此系统可以测量大电机定子绝缘的超声波参数 ,从而使超声波技术成为一种绝缘老化状态的诊断方法 ;0 8MHz的探头对定子线棒老化早期的绝缘缺陷能得到特征明显的超声A扫描波形 ,为对绝缘介电性能有直接破坏作用的绝缘断裂性裂纹的检测和识别提供了方法 ,对预防因绝缘裂纹导致绝缘击穿、发电机非计划停机具有重要意义。与国际上相同领域内超声波斜入射的透射波法比较 。

Using the ultrasonic testing system developed,experiments are performed to practical stator bars with low frequency transducer probes.The results show that,with the 0 5MHz,0 8MHz,or 1 2MHz frequency probe,this system can receive the reflection pulse at the insulation copper interface.So it could be used for the insulation diagnosis of stator bar.For an aged stator bar,the 0 8MHz probe can detect the insulation defect.It could be applied to detection and recognition of insulation defect,and is of significance to prevent generator from unschemed stoppage.At last,the pulse echo method using straight beam probe proposed in this paper is compared with the transmission wave method using angle beam probe presented by J K Nelson,and found to be of a considerable application prospect..