氧化镁电缆的绝缘材料特性及载流量评估方法研究  

Study on insulating material characteristics of MgO cable and its ampacity evaluation method

作　　者：魏燕杰 刘英[1] WEI Yanjie;LIU Ying(State Key Laboratory of Electrical Insulation and Power Equipment,Xi′an Jiaotong University,Xi′an 710049,China)

机构地区：[1]西安交通大学电力设备电气绝缘国家重点实验室,陕西西安710049

出　　处：《绝缘材料》2024年第6期108-115,共8页Insulating Materials

摘　　要：为研究氧化镁电缆绝缘材料的特性及载流量评估方法,本文首先对氧化镁粉体进行了形貌观测和物相分析,确定其纯度及杂质成分;然后测量了氧化镁粉体的介电及导热性能参数,分析了受潮对材料介电参数的影响;最后提出针对氧化镁绝缘多芯电缆的等效热路模型及载流量简化解析算法,并通过二维数值仿真对解析算法进行了有效性验证。结果表明:干燥氧化镁粉体的体积电阻率在1012Ω·m以上,受潮会使其电阻率下降超过1个数量级;在10^(-1)~10^(4)Hz频率范围内,干燥MgO试样的介电常数约为7.9,介质损耗因数约为5×10^(-4)~5×10^(-3),受潮后介质损耗因数明显增大,特别是低频范围增幅明显;干燥MgO试样的电气强度为3.5~4.8 kV/mm,不同方法测得的数据有一定分散性;利用简化解析算法可对多芯氧化镁电缆的额定载流量进行准确评估,对于实际工程应用有利。In order to study the insulating material characteristics of MgO cable and its ampacity evaluation method,in this paper,morphology observation and composition analysis were conducted on MgO powder to determine its purity and inclusions at first.And then the dielectric and thermal characteristic parameters of MgO powder were measured,and the influence of moisture on the dielectric parameters was analyzed.Finally,an equivalent thermal curcuit model for MgO insulated multi-core cables and a simplified analytical algorithm for ampacity were proposed,which was validated by a two-dimensional numerical simulation model.The results show that the volume resistivity of dry MgO samples is higher than 1012Ω·m,which can decrease by more than 1 order of magnitude under the effect of moisture.In the frequency range of 10^(-1)‒10^(4)Hz,the dielectric constant of the dry MgO sample is about 7.9,and the dielectric loss factor is about 5×10^(-4)‒5×10^(-3),which increases significantly after being moisture exposed,especially in the low frequency range.The electric strength of the dry MgO is 3.5‒4.8 kV/mm,and the data measured by different methods have a certain degree of dispersion.The rated ampacity of MgO insulated multi-core cable can be evaluated accurently by using the simplified analytical algorithm,which is beneficial to practical engineering applications.

关 键 词：防火电缆 氧化镁绝缘 材料特性参数 额定载流量 

分 类 号：TM215[一般工业技术—材料科学与工程] TM247[电气工程—电工理论与新技术]