电缆等温松弛电流的时间特性与温度特性研究

Time Characteristics and Temperature Characteristics of Cable Isothermal Relaxation Current

为研究极化/去极化时间和温度对电缆等温松弛电流(IRC)测量的影响,在不同实验条件下对10 kV交联聚乙烯(XLPE)电缆进行IRC测量。结果表明:增加极化时间可以提高测量结果的可靠性,极化时间不小于600 s时可获得较为准确的测试结果,极化时间在1200~1800 s时可有效提高IRC测量结果的准确性与老化因子A的稳定性。此外,去极化电流的分峰曲线会随去极化时间的增加而逐渐向时间轴增大的方向移动。随着测试温度的提高,去极化电流呈现先减小后增大的趋势。在较低温度范围内,温度升高会促进极化过程中电荷的脱陷行为,因此在去极化过程中较少的电荷脱陷行为导致较小的去极化电流;在较高温度范围内,温度升高会增大材料的电导率并促进去极化过程中深陷阱电荷脱陷,因此导致去极化电流增大。最后,基于上述实验条件,对不同老化程度的模型电缆进行IRC的检测,验证了该测量方法对电缆绝缘老化检测的灵敏性与绝缘状态评估的可行性。

In order to study the effects of polarization/depolarization time and temperature on the isothermal relaxation current(IRC)measurement of cable,we conducted the IRC measurement on 10 kV cross-linked polyethylene(XLPE)cable under different experiment conditions.The results show that increasing the polarization time can improve the reliability of measurement results.The test result is more accurate when the polarization time is no less than 600 s,and the accuracy of IRC measurement and the stability of ageing factor A can be improved effectively when the polarization time is in 1200–1800 s.In addition,with the increase of depolarization time,the peak-dividing curves of the depolarization current move to the increasing direction of time axis.With the increase of test temperature,the depolarization current decreases at first and then increases.In a lower temperature range,increasing the temperature can promote the detrapping of charge during the polarization process,therefore the depolarization of less charge leads to the smaller depolarization current.In a higher temperature range,increasing the temperature will increase the conductivity of material and promote the detrapping of deep trap charge during the depolarization process,which makes the depolarization current increase.Finally,on the basis of above experimental conditions,the IRC of the model cables with different ageing degrees was tested,and the ageing detection sensitivity and the insulating state evaluation feasibility of this method for cable was verified.