Influence Analysis of the Grounding Grid of Communication Tower Base on Lightning Signal

Communication tower is often close to machine room. When the lighting strikes the communication tower, it raises electrical potential of grounding grid and transient ground potential raise could damage weak electrical equipment in machine room. In order to solve this problem, in this paper, a response calculation model under the condition of the lightning transient was established, which was based on the construction drawing of a communication tower and machine room grounding grid in Bao-Lan PDL (Passenger Dedicated Line). This model analyzed potential changes under the conditions of various factors when the lightning current injected grounding grid, including two grounding grid is equipotent connected or not, different distances and soil resistivity between two grounding grid, etc. Computational results show that transient ground potential of the machine room can reduce by 70% when the distance of two grounding grid increased from 5 to 20 m, and transient ground potential can be 10 times higher when two grounding grid is equipotent connected. Finally, the propose suggestions related to requirements engineering based on these analysis.