Improving the Grounding System in 33/11 kV Distribution Substations

Abstract

The grounding is the connection of the metal structures of machines and electrical equipment in locked connection with the ground to prevent destructive potential. Besides, to connect the neutral point in the three-phase networks to the ground directly or through resistors. According to the international standards, the agreed grounding resistance should be 1 Ω or lower. It is challenging to get the standard value of grounding resistance under various environmental conditions. Therefore, to manage troubled environments, the Bentonite substance was proposed to use, considered soil substitute and filler material for electrical grounding applications. The ground resistance network of the 33/11 kV substations with closed electrodes mixed with Bentonite was examined and measured the resistance performance of the ground network at various anchorage points for one month. The results showed a considerable decrease in the earth resistance in the network that contains a certain percentage of the substance Bentonite. Those resistors' performance was studied utilizing an earth tester device and the simulations of these networks through the ETAP program. The on-site obtained resistance confirmed the simulation study when mixed with Bentonite material and it was significantly reduced. In addition, the proposed material could maintain acceptable small ground resistance under various conditions.