On the interaction of 132 kV transmission system with communication line: Street cabinet resistivity evaluation

Occurrence of surge voltages and surge currents in low-power circuits is initiated primarily because of two sources, i.e, natural lightning and switching phenomena; the other source of surge occurrence is possibly due to the interaction of power systems and communication system. Results have indicated that soil resistivity is crucial in determining the adequacy of an earthing system. In region with the highest resistivity, the EPR and the scalar potential of the cabinet are very high. Remarkable low induced voltages at 200 m away from the power line when subjected to a single phase-to-earth fault was observed. At 50 m away, step and touch voltages could be dangerous due to the nature of soil in the vicinity. In addition, a 132 kV double circuit transmission line sharing the same corridor with a telecommunication line was also investigated and have also shown the induced voltages in the order of thousand volts on the cable due to a single phase-to-earth fault. Cables must be protected from such dangerous voltages. During normal peak load conditions voltages are considered not to inflict any damage to equipment and livestock.