Impulse Characteristics Test and Structural Optimization Selection of Tower Grounding Devices Under High Resistance Geological Conditions

To master the true impulse characteristics of tower earthing devices in high-resistance areas and improve the technical and economic efficiency of tower grounding device design, lightning impulse high current tests were conducted on several real tower grounding devices under high-resistance geological conditions of Xizang high-altitude test base, and the impact characteristics were analyzed in relation to factors such as the angle, length, and quantity of rays.. Futhermore, a simulation calculation model for the impact characteristics was established, and the optimization selection method for the structure of grounding devices was analyzed. The results indicate that the impact grounding impedance is the smallest when the ray is at the 135° angle in the structure of a square frame with four rays. As the length of the ray increases, the impact grounding impedance decreases, but there is an effective length. After exceeding the effective length, continuing to increase the length will result in a small reduction in impedance. When the overall length of the earthing body remains constant, redesigning the grounding device to have more rays when the ray length exceeds the maximum length can further reduce impedance. The impedance reduction effect of branch rays set at the beginning of the main ray is better than that at the middle and end.