Low Power Loss Online Monitoring of High Voltage Cable Sheath Faults Based on Differential Current Principle

This paper proposes a novel online monitoring method for cable sheath faults. Based on the differential current principle, a current lead-out point is set at differential current balance point of the double-ended grounding cable sheath. The lead-out point is connected to the detection device and grounded to form two differential current circuits. When under normal condition, the current of the two differential current circuits is balanced, and there is no current flow in the detection device, which will not cause power loss. When sheath grounding fault occurs, the two differential current circuits are unbalanced, and the detection device is activated, sending a signal to personnel. Since the detection device is only awakened when there is fault occurs, in a dormant state when the cable line is working normally, it is more economical and durable, and can be used as an alarm device for the fault of sheath grounding. Compared with the traditional method, this method has higher economy and durability, and is of great significance for the safe operation of urban power grid.