Study On Ultrasonic Testing In Porcelain Post Insulators With SH Wave

In the long run process, porcelain post insulators are very easy to crack because of various stress function. This kind of situation is a serious threat to service safety of power system. More than95%of the porcelain insulator crack occurred from30mm inside flange to first porcelain, so it’s very necessary to detect the crack exactly. Now some ultrasonic testing methods can be used to realize the crack detection, but we also found many problems in the detection process:the sensitivity and signal-to-noise ratio of climb wave are low, the maximum effective detection range is only about50mm; small angle longitudinal wave transducers is difficult to identify the crack if the crack is very small, the validity and reliability of the test is low.In order to improve the effect on ultrasonic testing in porcelain post insulators, based on theoretical analysis, this paper proposed a new detection method to detect the surface or near surface defects in porcelain post insulators-the horizontally polarized shear wave method. To determine the application feasibility of ultrasonic testing of surface or near surface defects in porcelain post insulators with SH wave, piezocomposite chip with2-2connectivity and SH wave transducers have been developed. At the same time, the performance testing of piezocomposite chip and SH wave transducer has been done.In order to study the sound attenuation and signal to noise ratio of SH wave, artificial defects in the surface of the porcelain insulator block was tested respectively by SH wave and creeping wave.Experimental results show that SH wave can achieve the purpose of testing surface or near surface defects in porcelain post insulators. The defect detection sensitivity and the signal-to-noise ratio are better than creeping wave. The sound attenuation of SH wave is smaller than creeping wave in porcelain insulators. And because of this feature, SH wave can propagate longer and can find a wide range of defects.