Digital Simulation and Analysis of Surges on Polyphase Transmission Lines with Earth Return

A method of analysis and a digital simulation of surges on polyphase EHV transmission lines with earth return are presented. The analysis allows mathematical calculations of switching surge wavefronts and gives a better insight into the distortions of the waves due to the earth-resistance. This digital simulation is easy and straightforward. It is based on the property "the more the ground-mode propagates, the more its delay increases". Simulated curves are found to be in good agreement with analytical results and with test oscillograms.