Earthing Resistance Tester developed using Resonant Circuit Technology with No Auxiliary Electrodes

This paper presents an earthing resistance tester that uses resonant circuit technology to operate with a simple earthing electrode and without auxiliary electrodes. The measurement mechanism is analyzed using an earth return circuit model. The earthing electrode being tested, a lead wire, a return wire and the soil itself comprise the earth return circuit (LRC serial circuit). The requirements for this measurement method are obtained from numerical simulations, taking the lengths of the lead wire and the return wire to be 1 m and 20 m, and soil resistivity less than 10-2 s/m. The developed tester can measure the earthing resistance by evaluating the loop impedance of the earth return circuit at its resonant frequency, using a resonant frequency in the range of 100 kHz to 1.5 MHz. The return wire need only be placed on the soil surface without any termination. Earthing resistance measurements made by the developed tester and a conventional tester (3-pole method) differed by less than ±20% for earthing resistance values between 50 Ω and 400 Ω. The developed tester is a good way to test a simple earth electrode with an earthing resistance value of around 100 Ω. Key-Words: Earthing resistance, an earth return circuit model, tester, without auxiliary electrodes, resonant frequency, experiments and examinations