Experimental Study on Influence Factors of Capacitive Coupling of Adjacent Directly Buried Cables under Impulse Current Considering Soil Discharge Channel

Independent grounding electrodes are often set in the grounding system for lightning protection. When lightning current enters the ground through the independent grounding electrode, it will cause electromagnetic interference to the nearby secondary cables. When lightning flows into the ground, it is usually accompanied by the generation of soil discharge channels. And the randomness of channel spatial structure will affect the transient electromagnetic field distribution, thereby affecting the electromagnetic interference process. In order to explore the influence of soil discharge on the capacitive coupling process of electromagnetic interference of secondary cables in the ground, an experimental observation platform is built to carry out the simulation experiment of cable capacitive coupling under impulse current, the image data of soil discharge channel and the voltage and current waveform of grounding electrode and shield of cable are collected. The results show that the capacitive coupling current waveform of the shield of cable is consistent with the first derivative law of impulse voltage waveform of grounding electrode; The spatial structure of soil discharge channel and the water and salt content of surrounding soil have a significant effect on the capacitive coupling current.