高压电缆缓冲层烧蚀过程中电流密度与气体产物浓度的关联性研究

Study on correlation between current density and gas product concentration of buffer layers for high-voltage cable during ablation process

高压电缆缓冲层在烧蚀过程中会生成气体产物,然而目前对于烧蚀过程中气体产物浓度与缓冲层导电性能的关联性尚不明确。为此本文开展了电缆缓冲层烧蚀模拟实验,研究缓冲层烧蚀过程中电流密度与气体产物浓度的演变规律。结果表明:在干燥与潮湿条件下,缓冲层的电流密度均随烧蚀时间延长呈现出双指数函数衰减的规律,且电流密度衰减速率随烧蚀时间增加呈先快速降低后基本不变的趋势,仅潮湿试样在烧蚀初期电流密度出现峰值。气相色谱测试结果表明,潮湿条件下缓冲层在烧蚀过程中的气体产物包括CO_(2)、H_(2)、CO、CH_(4)、C_(2)H_(4)、C_(2)H_(6)、C_(2)H_(2)共7种。在干燥与潮湿条件下,缓冲层烧蚀的气体产物浓度均随烧蚀时间延长先迅速增大后趋于稳定,气体浓度增长时间与电流密度下降时间一致,二者随烧蚀时间的变化规律密切相关。分析认为,烧蚀过程中缓冲层电流密度的衰减速率与气体产物的生成速率具有关联性,烧蚀气体产物浓度的变化反映了缓冲层烧蚀破坏的严重程度。

The buffer layer of high-voltage cable will generate gas products during the ablation process.However,the correlation between the gas product concentrations and conductive property of buffer layer during the ablation process is still unclear at present.Therefore,we conducted a simulated ablation experiment on cable buffer layer and studied the evolution law of current density and gas product concentrations during the ablation process of buffer layer.The results show that under both the dry and wet conditions,the current density of buffer layer exhibits a bi-exponential function decay law with the increase of ablation time,and the decay rate of current density shows a trend of decrease rapidly at first and then unchanged basically with the increase of ablation time,only the wet sample exhibits peak current density during the initial stage of ablation.The gas chromatographic test results show that under the wet condition,the gas products during the ablation process of buffer layers are CO2,H2,CO,CH4,C2H4,C2H6,and C2H2.Under both the dry and wet conditions,the gas product concentrations increase rapidly at first and then tend to a stable value with the increase of ablation time,and the increase time of gas concentration is consistent with the decrease time of current density,which indicates the change laws of current density and gas concentration with the ablation time is closely related.It is analyzed that there is a correlative relationship between the current density decay rate and the gas products generation rate during the ablation process of buffer layer,and the variation of gas product concentration can reflect the severity of buffer layer ablation.