Cable circulating current (mainly sheath circulating current) is the most common electromagnetic induction problem in the operation of single-core high-voltage cables. When alternating current flows through the core of a single-core high-voltage cable, an alternating magnetic field is generated, which induces an electromotive force in the metal sheath. When the sheath is grounded at both ends/multiple points, the cross-connection system fails (transposition error, coaxial cable breakage, water ingress in the box), the three-phase arrangement/ load is unbalanced, or the sheath insulation is damaged or accidentally short-circuited, the sheath and the ground or metal components form a closed loop, and the electromotive force drives the generation of sheath circulating current. The magnitude of the circulating current is closely related to the load current, cable length, and grounding method. The sheath can cause heating, loss, insulation aging, and in severe cases, lead to faults.
In November 2025, Xiangyang Power Supply Company discovered during cable inspection that some 110kV cable wells had been leaking water for a long time, causing the grounding boxes to rust and the loop resistance to be abnormal. The sheath circulating current hazard was prominent. The company adopted the lead sealing process to reseal the joints, eliminate the grounding loop fault, and ensure the safe operation of the line.
Real-time online monitoring schemes for cable sheath circulating current have become the mainstream solution. For example, the HIZ-SD-HL cable grounding circulating current monitoring system from Guangxi Haizhuo Technology can detect the circulating current data of grounded cables in real time and transmit the data to the monitoring center via optical fiber and 4G/GPRS/RJ45. The specific location is displayed on the electronic map of the monitoring center, allowing line maintenance personnel to keep track of the cable operation status at any time.
