二次回路直流电缆PVC绝缘材料热老化特征研究

Research on Thermal Aging Characteristics of PVC Insulation Material for DC Cables of Secondary Circuit

摘要:

二次回路直流电缆老化会严重影响变电站安全运行。对电缆的聚氯乙烯（PVC）绝缘材料进行人工加速老化，经过不同温度和老化时间，采用热失重和傅里叶红外光谱对老化样本进行分析，探究其在不同条件下的老化特性。结果表明在PVC热失重的两个阶段，当老化温度相同时，延长老化时间会使PVC树脂在热失重第一阶段损耗增加、残留物减少，尤其是老化温度为120 ℃及130 ℃时这类变化趋势更加明显。傅里叶红外图像证实提高热老化温度和延长热老化时间会导致PVC电缆中甲基、亚甲基、羟基、碳碳双键等官能团增多，特别是当老化温度为120 ℃或以上时增加趋势更为明显，且随老化时间的延长呈加速趋势。因此当温度达到120 ℃时，二次回路直流电缆PVC绝缘材料将呈老化加速趋势。

Abstract:

The aging of secondary circuit DC cable will seriously affect the safe operation of substation. The artificial accelerated aging of PVC insulation material of the cable is carried out, after different temperatures and aging time, the aging samples are analyzed by thermal weightlessness and Fourier infrared spectroscopy to explore its aging characteristics under different conditions. The results show that in two stages of PVC thermal weightlessness, when the aging temperatures are the same, prolonging the aging time will increase the loss of PVC resin in the first stage of thermal weightlessness and reduce the residue, especially when the aging temperature is 120 °C or 130 °C, this kind of change trend is more obvious. The images of Fourier transform infrared spectroscopy (FTIR) confirm that increasing thermal aging temperature and prolonging thermal aging time will lead to an increase in functional groups such as methyl, methylene, hydroxyl and carboncarbon double bonds in PVC cables, and the trend of increase is more obvious especially when the aging temperature is 120 °C and above, and the trend is accelerated with the prolongation of aging time. Therefore, when the temperature reaches 120 °C, the PVC insulation material of secondary circuit DC cable will be in accelerated aging trend.