الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Several principles, methods and devices were, and are still being used to protect medium voltage transmission lines.
Each protection and fault signaling system considers several factors, among them the protection degree required, the response time, the nature of the terrain and weather over which the transmission line passes. The protection system cost is not the absolute measure for its performance quality since the system design should achieve the desired issues of the protection mechanism. From the engineering point of view, only one protection system is appropriate for a certain problem. To achieve some national targets such as rapid extension of the power network while keeping low cost, the protection system should be modified to match these conditions. Protection system design should not consider these additional factors to the limit that neglects tire protection and safety theories. Due to the fast development plans in several parts of Egypt, such as the Upper Egypt, the new towns and rural areas, there is a huge need for fast, efficient and reliable protection systems. To conclude we seek a protection system mat achieves the required protection tasks and have several features. First, it should have low cost requirements. Second, it must offer full protection to the medium voltage transmission line also it should provide a capability of fast fault location with automatic fault isolation for the faulty section of the transmission line. Finally it should be designed using simple hardware that make it easily manufactured and developed locally.