Electrical Engineering Report: Overcurrent Protection in Power Systems

This report provides a comprehensive overview of overcurrent protection in power systems. It begins by defining normal and abnormal operating states, highlighting the significance of overcurrent protection in preventing equipment damage and ensuring human safety. The report explores various fault types, including three-phase faults, line-to-line faults, single-line-to-ground faults, and line-to-line-ground faults. It emphasizes the critical role of overcurrent protective devices (OCPDs) in mitigating the dangerous effects of overcurrents and short-circuit currents. A literature review summarizes key concepts and techniques, including the application of overcurrent and earth fault relays, integrated protective relays, and networking of protection relays in substations. The report also discusses the sources of fault current in radial distribution systems, emphasizing the factors that influence fault current magnitude, such as source contribution, transformer impedance, and motor contribution. The report concludes by highlighting the importance of accurate fault current estimation for effective overcurrent protection.