基于临界折射纵波法的盆式绝缘子法兰螺栓松动检测

Detection on Looseness of Flange Bolt of Insulating Spacer Based on Critical Refraction Longitudinal Wave Method

盆式绝缘子是GIS的关键绝缘器件,与两侧气室法兰通过螺栓进行紧固连接,当螺栓松动时会导致盆式绝缘子应力分布不均,从而影响GIS运行的安全性和稳定性。文中提出了一种基于超声临界折射纵波(L_(CR))的盆式绝缘子法兰螺栓松动检测方法,根据L_(CR)波在盆式绝缘子法兰表面的传播声时差来反映螺栓松动情况。结果表明,当相邻螺栓松动时,L_(CR)波在松动螺栓之间的法兰表面声时差变化最大,且变化量大于24 ns;当不相邻螺栓松动时,L_(CR)波在松动螺栓正对的法兰表面声时差变化最大,且声时差变化量大于10 ns,并且螺栓松动程度越大,超声传播声时差变化量越大。该检测方法可实现对盆式绝缘子法兰螺栓松动的检测,判断螺栓松动数量及位置,具有一定的工程实用价值。

Insulating spacer is the key insulation element of GIS.It is fastened and connected with the flanges of the gas compartment on both sides by bolts.The bolts,in case of loose,will lead to uneven stress distribution of insulat-ing spacer,thus affecting both safety and stability of the insulating spacer.In this paper,a method for detecting the bolt looseness of insulating spacer flanges based on ultrasonic critically refracted longitudinal waves(L_(CR))is proposed.The looseness of bolts is reflected in accordance with the acoustic time difference of L_(CR) wave propagation on the sur-face of the insulating spacer flanges.The results show that,in case of looseness of the adjacent bolts,the L_(CR) wave has the largest change in the flange surface acoustic time difference between the loose bolts,and the magnitude of variation is greater than 24 ns;While,when the non-adjacent bolts are loose,the acoustic time difference on the surface of flange of L_(CR) on the opposite side of the loose bolt is maximum and the acoustic time difference is greater than 10 ns,and the greater the bolt looseness,the greater the ultrasonic propagation acoustic time difference.The de-tection method can achieve the detection of the looseness of the flange bolts of the insulating spacer,judge the num-ber and position of the loosening of the bolts and has certain engineering practical value.