*Article* **Detecting Grounding Grid Orientation: Transient Electromagnetic Approach**

#### **Aamir Qamar 1,***∗***, Inzamam Ul Haq 2, Majed Alhaisoni 3 and Nadia Nawaz Qadri 1**


Received: 7 November 2019; Accepted: 2 December 2019; Published: 4 December 2019

**Abstract:** The configuration is essential to diagnose the status of the grounding grid, but the orientation of the unknown grounding grid is ultimately required to diagnose its configuration explicitly. This paper presents a transient electromagnetic method (TEM) to determine grounding grid orientation without excavation. Unlike the existing pathological solutions, TEM does not enhance the surrounding electromagnetic environment. A secondary magnetic field as a consequence of induced eddy currents is subjected to inversion calculation. The orientation of the grounding grid is diagnosed from the equivalent resistivity distribution against the circle perimeter. High equivalent resistivity at a point on the circle implies the grounding grid conductor and vice versa. Furthermore, various mesh configurations including the presence of a diagonal branch and unequal mesh spacing are taken into account. Simulations are performed using COMSOL Multiphysics and MATLAB to verify the usefulness of the proposed method.

**Keywords:** grounding grid; magnetic field; orientation; transient electromagnetic method (TEM)
