Abstract
This paper presents AC substations grounding system for either conventional or gas-insulated. The design of grounding systems of substations has the primary purpose of ensuring the safety and well being of personnel, who may become electrically coupled to the grounding mats during unbalanced fault conditions (El-Dessouky, El-Aziz, & Khamis, 1998), (Phan, 1990). In general, an unbalanced fault will cause a ground potential rise of the system neutral and any conductive medium electrically connected to the neutral. The approach of this design is based on the IEEE Standard 80-2000 which discusses the following subjects safety in grounding, tolerable body current limit, primary and auxiliary ground electrodes, grounding enclosure sizing of conductors and materials, soil characteristics, ground resistance, types of ground faults, installation of connections, pigtails, ground rods, and ground grid integrity test. In this project, general system structure as well as rules and data representations are discussed. An illustrative example is presented using 15 kv medium voltage switchgear for Tri-Met Portland Westside light rail (Thomas & Pham, 1999). The ac substations grounding system design presented in this project can assist grounding system engineer to obtain a safe grounding system which is one of most important design aspects of substations.