Feasibility of Remote Earth Monitoring for SWER Systems

Single Wire Earth Return (SWER) is an example of engineering brilliance which is elegant in its simplicity. The design involves one high voltage conductor with the mass of the earth acting as the path for the return current and as a protective measure to dissipate fault currents. The connection between the earthing conductors and ground is an integral component of the SWER distribution system and it is essential for electricity providers to maintain reliable low resistance connections. SWER was originally developed as a cost-effective alternative to supply customers in rural and remote areas. Australia has approximately 200,000km of active SWER line across the States and Territories with Queensland’s Energy Queensland operating and maintaining the largest portion of 65,000km. Ergon Energy, a subsidiary of Energy Queensland, has 26,066 SWER earths to maintain on a rolling six year cycle. Currently the only inspection method for SWER earth connections is with an instantaneous reading taken via a field visit to each site. Soil is non-homogeneous by structure causing this instantaneous measurement to reflect the chemical composition and level of moisture in the soil at one point in time. This can cause erroneous measurement results due to the influence of seasonal and local effects on soil conditions and makes trending analysis difficult. This research project provides a feasible theoretical non-intrusive method to remotely monitor live SWER earths without the need to drive test electrodes. The calculations and simulated models are correlated against baseline conventional earth testing methods and field test results. The stretch target aims to procure a prototype online monitoring unit and build a test site