压力注入电压稳定剂对热氧老化电缆绝缘性能的增强机理

为了研究压力注入电压稳定剂对热氧老化电缆的修复效果,通过配置修复液对电缆样本进行注入修复,研究修复液对电缆绝缘性能的增强效果及作用机理。选取抗氧剂300和二茂铁配置不同添加浓度的7种硅氧烷修复液,对热氧老化电缆样本进行注入式修复,测试修复前后XLPE绝缘的电树引发电压、直流电导率和介质损耗因数,对部分样本进行二次老化,并测试不同老化时间的氧化诱导期和电树引发电压。结果表明,注入2种类型的电压稳定剂均能够大幅提高热氧老化电缆的电树引发电压,但也会在一定程度上增大电导率和介质损耗因数;注入抗氧剂300能够提高热氧老化电缆的氧化诱导时间,并在较长时间内提升其抗热氧老化和抗电树能力。由扩散公式与实验结果可知,通过增大注入压力,升高扩散温度,选择有效浓度区间更大的电压稳定剂,选取较为保守的添加含量等措施,使电压稳定剂在绝缘层中的浓度分布处于有效浓度区域,是保证修复效果的有效措施。

Enhancement Mechanisms of Voltage Stabilizer Injection on Insulation Performances of Thermal-oxidative Aged Cables

In order to study the effect of voltage stabilizer injection on thermal-oxidative aged cables, rejuvenation fluid was prepared and injected into the cable samples. The insulation property changes were investigated. Seven rejuvenation fluid with different added concentrations of antioxidant 300 and ferrocene were prepared and injected into the thermal-oxidative aged cable samples. The electrical tree initiation voltage, DC conductivity and dielectric loss factor of the samples were investigated. Then we performed second aging on part of samples and investigated the oxidation induction time and electrical tree initiation voltage at different aging period. The results indicate that the injection of voltage stabilizer can greatly increase the electrical tree initiation voltage of the thermal-oxidative aged cable. However, the conductivity and dielectric loss factor were also increased. The injection of antioxidant 300 can increase the oxidation induction time and improve the thermal-oxidative aging resistance of the cable samples for a long duration. The formula of fluid-polymer diffusion model shows that increasing the injection pressure, raising the temperature, increasing the solubility of the voltage stabilizer in XLPE, and selecting conservative addition are effective measures to ensure the rejuvenation effect.