Failure Analysis on Galvanized Steel-tube Pole Used for Supporting Electrical Equipment in 500 kV Substation

Abstract

Electrical equipment in substation plays a key role in power transmission and distribution, which is usually supported by the steel-tube pole. In recent years, more and more crack defects were found in steel-tube pole used for supporting electrical equipment in substations, thus the safety and stability of power grids is severely affected. In this paper, the cracked steel-tube support of electrical equipment in a 500kV substation was investigated by means of macro-morphology inspection, chemical composition analysis, mechanical properties test, microstructure analysis, water sample analysis and fireworks experiment. The result showed that there was a grouting hole with poor sealing in the top of the steel-tube pole, so the rainwater and snowmelt could flow into the tube through the gaps. Once the temperature dropped abruptly, the water inside the tube would freeze and expand, led to the bursting of the steel-tube pole. Finally, effective suggestions were put forward, which could ensure the electrical equipment operating safely and stably.