INDUCTANCE OF SQUARE GRIDS.

Square or rectangular grids, used for grounding in high voltage substations, are made of bare conductor buried at a uniform depth in parallel lines. The inductance of the grounding grids plays an important role in determining the behaviour of the grids when discharging impulse lightning current to the ground. A method to determine the inductance of square grids having uniform square meshes is presented in this paper. The feeding point of the current has been taken to be either at the centre or at one of the corners of the grid. The method is applied to the grids having dimensions usually encountered for grounding grids in high voltage substations. From the results, an empirical formula to determine the inductance of a square grid of any size and any number of meshes is evolved. The results can be extended to compute the inductance of a plate.