| 摘要 |
A structure for protecting an underground transmission line using circulation current reduction is provided to minimize power loss by maintaining a sheath circulation current under a set value to reduce an induced voltage in a normal power transmission state. A structure for protecting an underground transmission line using circulation current reduction includes a cross bond lead line(20), and a sheath circulation current reducing unit(22). The cross bond lead line(20) is connected between underground cables(14) by a cross bond grounding method with respect to an insulating connection box(18) when more than one insulating connection box(18) are arranged along the underground cable(14). The sheath circulation current reducing unit(22) is installed along the corresponding underground cable(14) on the cross bond lead line(20). In a normal power transmission state, the sheath circulation current reducing unit(22) has an impedance corresponding to an impedance set value, and flows a sheath circulation current under a set value to reduce an induced voltage and increase a transmission capacity. And in an abnormal power transmission state, the sheath circulation current reducing unit(22) has an impedance under the impedance set value, and flow a fault current to protect a power transmission system.
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