Analysis and Suggestion on String Breakage Failure of Glass Insulator in 500kV Transmission Line

The accident of a 500kV transmission line glass insulator string breakage failure was analyzed. It was found that the inner side of the glass insulator head was smooth and flat, the steel foot and cement came out, the outer surface of the cement was smooth, and there was no groove on the glass insulator head. The appearance inspection, mechanical damage, impact breakdown and residual strength etc. of 46 units LXHP4-160 glass insulators of the same phase were carried out, no unqualified items were detected in the test. The analysis shows that the insulator manufacturer lost the technological link in the manufacturing process, failed to make the thread in the inner side of the insulator glass head in strict accordance with the product design drawing, and the friction between the inner side of the glass head and the cement joint surface was not enough, resulting in the steel foot falling off.