Method for Reducing Impulse Grounding Impedance of Grounding Device by Using Grounding Electrode with Non-uniform Radius

Reducing the transient grounding impedance of the grounding device is an important measure for lightning protection. However, due to the inductive reactance of the grounding electrode, the transient grounding impedance is usually very high. This paper analyzes the parameters that affect the inductive reactance of the grounding electrode, and studies the influence of the electrode radius on the inductive reactance. Considering the cost and the effective current leakage length of the grounding electrode, a method of reducing the transient grounding impedance is proposed. That is using a piece of grounding electrode with large radius near the current injection point of the grounding device, and then gradually reducing the radius along electrode. The effectiveness of the method is verified by numerical simulation, and the optimal arrangement is analyzed. It can be seen that the method can greatly increase the effective current leakage length of the grounding electrode and reduce the transient grounding impedance of the grounding device.