For a long high-voltage single-core cable, when there is an AC current passing through the core of the cable, its metal sheathing will generate an induced electromotive force due to electromagnetic induction, which will inevitably result in a ring current under the condition of grounding at both ends. Normal ring current in the design of the permissible range will not cause harm to the cable, because the cable in the design and manufacturing process has taken into account this situation, its metal sheath and insulation and other parts of the ability to withstand the impact of the corresponding ring current. However, there is always a but - the cable in the laying process, the metal sheath may be damaged by external forces and contact with the surrounding grounding objects, the formation of additional grounding path, in which case, the loop current will be outside the normal range, so that the metal sheath heating, accelerated insulation aging.
In addition, poor grounding connections, corrosion of the insulation layer, damaged by external forces or localized discharges, etc., may also lead to a decline in the insulation between the cable core and the metal sheath, at this time, there may be a part of the core current leakage to the metal sheath, resulting in anomalous circulating currents, which is an important symptom of the cable failure.
Therefore, for the unfolding of the cable sheath ring current monitoring, is to ensure that the power cable hidden danger in advance of the perception of an important link. DX-DLS100-HL Cable sheath ring current monitoring device is able to monitor the cable sheath of transmission and distribution cables. Ring current monitoring device can be able to transmission and distribution substation lines of grounding ring current data detection, in the CT induction + photovoltaic power take the energy to ensure that the work of the kinetic energy based on the installation of sensors in the cable grounding line to monitor the collection of the cable metal sheath of the changes in the size of the ring current current, and transmitted to the monitoring host to analyze and deal with the diagnosis, early warning, the external grounding ring current sensors can be used to monitor the cable sheath of the cable sheath of the cable sheath. The number of external grounding loop current sensors can be more than 3 sets.
The following picture is the installation site of our cable sheath ring current monitoring device in Jiangxi:
