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Analysis of the incidence of grounding with high resistivity against atmospheric discharges in the sub - Transmission line of 69KV San Rafael - Mulalo

Abstract:

Electrical sub-transmission systems must ensure the reliability of the electrical system in the event of sudden changes in voltage and current, especially when there are atmospheric discharges. This document shows the influence of high resistivity on grounding, connected to guard wires in the San Rafael - Mulaló 69 KV Subtansmision line of ELEPCO S.A. By means of a field study, there are resistivities ranging from 15 Ω to 19 Ω which for simulation conditions was taken into account an average of 75.89 Ω but according to the IEEE-80 standard should be less than 10 Ω for lightning protection. Under these conditions according to the simulation, in the face of an atmospheric discharge of 27,37 kA, a stability in the time of 0.07s is obtained, this causes that according to the calibration of the zones of operation activates other equipment of protection that They do not respond to the fault. If grounding is less than 10 Ω, peaks of 1.0448 kA are obtained and a stability of 0.015 secons is achieved, this time allows to guarantee the reliability of the system and to improve the quality indexes FMIK and TTIK which are regulated by the CONELEC.