热氧老化EPR电缆绝缘局部放电特性及劣化机理

为了探究热氧老化后乙丙橡胶电缆绝缘的局部放电特性及劣化机理,文中通过典型柱-板电极对不同老化程度的乙丙橡胶试样进行了局部放电试验,并对其放电发展特性和材料理化性质进行了分析.结果表明:放电起始电压和闪络电压均随绝缘老化程度的提高而降低;根据放电过程中放电特征量的变化规律,可将放电过程划分为4个阶段:起始阶段、发展阶段、...

Partial Discharge Characteristics and Degradation Mechanism of EPR Cable Insulation by Thermo-oxygen Aging

In order to investigate the partial discharge characteristics and degradation mechanism of EPR cable insulation after thermal-oxidative aging, the partial discharge tests of EPR samples with different aging degrees were carried out by typical column-plate electrodes, and the discharge development characteristics and physical and chemical properties of the materials were analyzed. The results show that the initial discharge voltage and flashover voltage decrease with the increase of insulation aging degree, and the discharge process can be divided into four stages according to the variation law of discharge characteristics during the discharge process: initial stage, development stage, continuous stage, and pre-flashover stage, and the PRPD spectra of samples with different aging degree show specific shapes in each stage. Surface gasification or gas desorption and the precipitation of additives lead to the appearance of "gully zone", "white block" and "micropore" on the surface of the sample. The increase of the number of free radicals such as carbonyl groups, polyethylene and polypropylene in the molecular structure is the key reason why EPR insulation is more prone to partial discharge after thermal oxygen aging.