煤矿井下动力电缆绝缘在线监测的研究

在分析比较现有动力电缆绝缘监测方法的基础上，针对煤矿井下电缆线路运行的特点，设计出了井下动力电缆绝缘在线监测系统。该系统采用低频信号注入法，即通过电抗器中性点对电缆注入低频信号，使低频信号源、电缆的对地绝缘电阻和大地构成回路。在注入低频电压一定的情况下，通过检测注入低频电流的大小，实现对电缆绝缘情况的在线监测，较好地解决了动力电缆绝缘在线监测可靠性差和灵敏度低的问题。通过模拟试验表明，该方法具有检测误差小、准确性高的特点; 既可对单条电缆绝缘进行监测，又可对多条电缆绝缘进行监测; 不仅可监测主电缆电路，同时还可监测多个分支电缆电路。

Research on Power Cable On-line Insulation Monitoring for Underground Coalmine

On the basis of the analysis and comparison of the existing power cable insulation monitoring methods，it designs the online monitoring system of the underground power cable insulation approach for the operational characteristics of the underground coalmine cable lines． The system uses the low-frequency signal injection method，injecting the low-frequency signal into the cable through the reactor neutral point． It constitutes a loop of the low － frequency signal，the cable insulation resistance and the Earth． Under the circumstances of injecting certain low-frequency voltage，it can achieve on － line monitoring of the cable insulation，by detecting the value of the low-frequency current-line，so the problems of poor reliability and low sensitivity on-line insulation monitoring of the power cable are solved better． The experiment shows that this method has a low error and high accuracy in detection; it can monitor not only the single cable insulation but also the multiple ones． It can apply to both the main cable circuits and the branch ones．