Electrical Tree Characteristics Of Epoxy Resin Under Ambient Temperature

With the rapid development of power industry and the expansion of power grid scale,the demand for power transmission is higher.Superconducting cable and HVDC transmission become the hot direction in the future.Epoxy resin insulation material is widely used in the accessories of high voltage direct current power cable and high temperature superconducting cable because of its excellent electrical performance and physical chemistry,and its performance is directly related to the safe operation of the transmission line.Electrical tree aging and breakdown are important reasons for insulation damage of epoxy resin insulation materials.Due to the complex working environment of the cable,the epoxy resin insulation materials need to withstand many tests,such as low temperature,high temperature,pulse voltage,DC voltage,etc.,and it is of great practical significance to study the growth characteristics of electrical tree under different temperature conditions.In this paper,the electrical tree branches in epoxy resin are studied.The growth characteristics of electric tree under low temperature,high temperature,pulse voltage and DC superimposed pulse voltage are analyzed.The growth mechanism of electric tree under different experimental conditions is discussed.The main conclusions are as follows:1.Using low temperature test platform to study the growth characteristics of epoxy resin electric tree.It is found that the low temperature has an inhibitory effect on the growth of electrical tree,and the initial probability of electrical tree decreases with the decrease of temperature.The growth morphology of electrical treeing in epoxy resin varies with temperature.In addition,in low temperature environment,electric tree branches are easier to initiate under wide pulse than narrow pulse.The growth rate of electric tree is faster,the breakdown time is shorter,and the aging damage area is larger.2.Using high temperature test platform to study the growth characteristics of epoxy resin electric tree.The experimental results show that,compared with the low temperature environment,the high temperature environment has an obvious promoting effect on the growth of the electric tree,and the initiation probability of the electric tree increases,the breakdown time shortens,and the epoxy resin is more prone to insulation failure.On the other hand,the increase of pulse amplitude and frequency accelerates the growth and elongation rate of the electric tree.3.Using DC superimposed pulse test platform to study the growth characteristics of epoxy resin electric tree.It is found that the electric tree is not easy to generate when the epoxy resin sample is simply applied DC voltage,and the superposition of the pulse voltage is beneficial to the initiation of the electric tree.The electric tree growth rate increases with the increase of the composite voltage amplitude,and the electric tree growth rate under the polarity complex voltage is slower.