Detecting faults in vertical grounding electrodes using rod insertion time domain reflectometry measurement

Abstract Breakpoints in vertical grounding electrodes, primarily caused by soil induced corrosion, can lead to faults in grounding systems. Diagnosing these faults is essential for ensuring both equipment protection and human safety. This paper presents a method and experimental verification for detecting faults in vertical grounding electrodes using rod insertion time-domain reflectometry. In this method, a secondary electrode is inserted next to the grounding electrode for facilitating a transverse electromagnetic propagating wave. An injected high rise-time pulse propagates and reflects from any impedance mismatch due to faults in the grounding electrode. By analyzing the reflected pulses for different secondary electrode depths, the presence of a fault and its location can be identified. A scale model is developed, where the injected pulse bandwidth, the grounding electrodes, and the electrical parameters of the ground medium are scaled to maintain the same transient pulse propagation characteristics as a full-scale case. The measurements demonstrate that both full breakpoints and partially damaged regions of the electrode can be identified. The experimental results show a deviation of less than 7% from both theoretical estimation and numerical simulations in the distance to a fault location.