SELF-GROUNDED POLE FOR POWER DISTRIBUTION GRIDS

Abstract

Grounding systems are intended to ensure the protection of the distribution grids equipments against voltage surges due to lightning strikes and internal system failures. However, assembling errors, deterioration over time, theft of grounding components, among others, contribute to decrease the reliability and security of the electrical grids. The self-grounded pole is a new grounding technology to protect distribution grids against voltage surges, mainly from atmospheric discharges, the main cause of power interruptions in distribution systems, presenting numerous advantages over the traditional system with grounding rods. This technology uses the internal steel reinforcement of the concrete as a grounding conductor of the electrical current to the base of the pole, which is composed of a specific concrete formula that results in a material with low electric resistivity, achieving better currents flowing performance to the ground. Laboratory tests with high voltage impulse applied to the pole (up to 60kV), resulted low surge impedance measurements, showing that the self-grounded pole can performing a good grounding function in electric energy distributions network. Tests in the CPFL group distribution utilities demonstrated that the grounding resistance with the use of self-grounded pole was better, at the same point, than the previous measurements with the conventional grounding rods system.