光缆护层对地绝缘电阻检测系统

为了能及时发现地下带金属护层光缆的破损隐患，提出一种通过检测光缆金属护层对地绝缘电阻大小来判断光缆是否破损的方法.该方法在光缆的金属铠装体上施加直流高压，利用采样电阻测量漏电流值，通过计算光缆护层对地绝缘电阻的实际大小判断光缆是否有破损.搭建了实际测量电路并对电路进行了仿真，结果表明，该系统最大可探测对地电阻为25MΩ，最低可探测故障对地电阻为5kΩ，证明了该方法具有一定的可行性和实际应用价值.

Detection system of cable sheath ground insulation resistance

In order to discover the hidden damage of the buried cable with metal sheath in time, a cable damage judgement method of detecting the cable metal sheath ground insulation resistance was proposed. The method applied DC high voltage on the metal sheath of the cable and detected the leakage current using the 〖JP3〗sampling resistance. The actual value of the cable metal sheath ground insulation resistance was calculated to judge the cable damage. The practical measuring circuit was built, and the circuit simulation was performed. The results indicate that the system can detect the maximum ground resistance of 25MΩ and the minimum fault ground resistance of 5kΩ. The feasibility and practical application value of the method get proved.