获取XLPE绝缘直流电压耐受指数的步进应力试验参数选取方法研究

Selection of Step-Stress Test Parameters for Obtaining DC Voltage Endurance Coefficient of XLPE Insulation

交联聚乙烯(XLPE)绝缘的直流电压耐受指数n是材料的重要性能参数,也是直流电缆绝缘厚度设计及出厂试验电压参数选取的重要依据。步进应力法作为一种高效的电寿命试验方法,其试验参数的选取对耐受指数n值的结果影响较大。该文提出一种步进应力试验的参数选取方法,该方法以累积损伤-时间(D-t)曲线、损伤矩阵D方差与n值关系曲线S(n)及S(n)曲线的二阶导数d^2S(n)/dn^2三个指标作为试验参数选取的依据。该方法为绝缘材料的步进应力和恒定应力电寿命试验结果的等效性评价提供了理论支撑。试验数据表明,通过该方法筛选的步进应力试验参数获得的电压耐受指数n值(n=12.0)与恒定应力下的结果(n=12.2)具有较好的一致性。

The voltage endurance coefficient is an important performance parameter of XLPE insulation,and is also of vital basis in cable design and selection of delivery test voltage.As a high-efficiency electrical life test method,parameter selection of the step-stress method has a great influence on the test results of the voltage endurance coefficient n.In this paper,a parameter selection method for step-stress test was proposed based on three indicators,i.e.cumulative damage-time(D-t)curve,variance of damage matrix D and n value relationship curve S(n),and second order of S(n)curve.These three indicators were used as the basis for the selection of the test parameters.This method provides theoretical support for the equivalence evaluation of the step-stress method and constant-stress method in electrical life test results of insulating materials.The experimental data show that the value of voltage endurance coefficient n(n=12.0)obtained by the step-stress test parameters screened by this method has good equivalence with the result under constant-stress method(n=12.2).