温度梯度叠加极性反转电压下硅橡胶电荷输运及电树枝特性

Charge Transportation and Electrical Tree Characteristics in Silicone Rubber Under Temperature Gradient Superimposed Polarity Reversal Voltage

直流电缆长期运行在高温度梯度作用下,且时常遭受极性反转、冲击电压等暂态电压,严重影响电缆绝缘可靠性。该文选用电缆附件主绝缘硅橡胶材料,针对不同温度梯度场和极性反转电压下的电树枝起始特性进行研究。搭建极不均匀场下双极性载流子输运模型,研究不同温度梯度和极性反转过程中电荷输运和电场分布特性。研究结果表明:随着针尖温度的上升,空间电荷注入量和注入深度不断增加,反转前后电场的变化更大。温度从30℃增加至120℃,电树枝起始电压下降26.2%,电树枝形态趋于密集,但电树枝长度先增加后减少。结合空间电荷输运特性,给出极性反转电树枝起始的过程,并分析温度梯度对电树枝引发特性的影响规律。

DC cables operate under high temperature gradients for a long time and are often subjected to transient voltages such as polarity reversal and impulse voltage,et al.,which seriously threatens the reliability of cable insulation.In this paper,silicone rubber,the main insulation material for cable accessories was selected,and electrical tree initiation characteristics with varied temperature gradient under polarity reversal voltage were studied.A bipolar carrier transport model under extremely inhomogeneous fields was built,and the charge transport ation and electric field distribution characteristics during different temperature gradients and polarity reversal voltages were studied.Results show that as the temperature of needle tip rises,the amount of space charge injection and the depth of injection continue to increase and the electric field changes more after the reversal.When the temperature increases from 30℃to 120℃,the tree initiation voltage decreases by 26.2%,and the tree morphology tends to be dense,but the tree length first increases and then decreases.Combined with the characteristics of space charge transportation,the initiation process of electrical tree under polarity reversal was given,and the influence of temperature gradient on tree initiation characteristics was analyzed.