超声法在支柱瓷绝缘子探伤中的应用

支柱瓷绝缘子存在的缺陷严重威胁电网的安全运行。介绍了采用超声法对支柱绝缘子进行探伤的基本原理,探伤方法主要有纵波斜角超声波检测和爬波超声波检测两种,纵波斜角超声波检测速度较慢,但可检测瓷件的中心部位;爬波超声波检测速度较快,探测表面下1～15mm的裂纹非常敏感。列举了采用爬波方法在现场检测的实例,建议:在停电时间允许的情况下,应结合爬波和纵波两种方法对支柱绝缘子内部的缺陷进行全面检测。检测时,根据瓷瓶的大小,选择合适尺寸的探头。同时还应根据被检瓷件的材料(高强瓷或普通瓷),选择同类别的试块和探头。

Application of Ultrasonic Detection in Post Insulator Overhaul

Inherent defects of porcelain post insulator constitute serious threat for service safety of power system.The basic principles of ultrasonic technology for porcelain post insulator detection are presented,which consists of longitudinal wave detecting with bevel probe and creep-wave detecting.The longitudinal wave detection with bevel probe has low velocity but it is advantageous for porcelain central kern detecting while the creep-wave has fast velocity and is sensitive for detecting cracks at 1～15 mm depth under the surface.The practice of on-site detection with creep wave is given.It is recommended to carry out defect detection on post insulators using both two longitudinal and creep-wave methods,If the power switching-off time is allowed.The adequate probes shall be chosen according to insulator size.The probes and test pieces of same porcelain material as that of tested insulator(normal or high strength porcelain) shall also be chosed.