Corrosion reaction kinetics and high‐temperature corrosion testing of contact element strips in ultra‐high voltage bushing based on the phase‐field method

Abstract

For the structural characteristics of power transmission equipment such as bushings, the plug-in structure is mostly used for current-carrying connections owing to the large size and long distance at high voltage levels. The contact element strip is the key component of the current-carrying structure, carrying the combined electrical–thermal effect. Its electrical current-carrying performance is important. In recent years, discharge failures caused by the overheating failure of electrical connections have occurred from time to time. However, there have been relatively few studies on the failure mechanism of the electrical connection structures of high-voltage power transmission equipment, such as bushings. In this study, from the perspective of corrosion reaction kinetics, a two-dimensional phase-field model of high-temperature corrosion is established to obtain the carrier concentration distribution in the film. The effects of temperature, gas partial pressure, film thickness, and applied electric field on the growth rate of corrosion reaction film were calculated using the finite element method. At the same time, with the contact element strips used in the bushing as the test object, a corrosion test was carried out in SF6 atmosphere to simulate the high-temperature corrosion caused by the uneven current carrying of the contacts in actual operating conditions. Combined with the effect of temperature on the film growth rate, the contact area was the most severely corroded location. The simulation can provide a qualitative analysis for the contact degradation test and a new method for studying the factors affecting the corrosion mechanism of contact element strips.