الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Electric power system include a large number and lengths of expensive and important power cable system of different ages, manufactures and installed over many decades.The oil paper installed in 1940s cables still in use where installed. Installation of XLPE cables started in the middle of the 1970s. Underground cables are very imported parts in a power system and are depended upon for reliable transmission and distribution services.Faults on the system can caused by many different phenomenon, however to date most of the investment made has been to increase the robustness of the MV and HV networks. Most major cities around employ underground LV network to supply their customers, as cables and construction remain static it becomes evident that each of these network are susceptible to the same types and frequencies of faults.The fault location in complex cables distribution systems is difficult, time consumingand labor intensive, consequently the cables fault location technique with high degree of accuracy and high degree of efficiency is increasingly demanded with the increased use of underground cables. Benefits of accurate fault location are quick repairs to restore power system, improvement of system availability and performance, reduction of operation cost, and saving of the time and expense of crew searching in bad weather and tough terrain. A variety of fault location techniques are used to achieve the above specified benefits. While numerous technique are now available to the fault locator, some technique can be destructive to the cables, some may require instruments not readily in stick, and other may involve detection methods not familiar to the user. Such challenge led to the need for a comprehensive fault locator reference manual. In the field of the fault location for underground cables, off line and on line methods are available. Off line methods are divided into two main groups; namely terminal methods and tracer methods. Terminal methods are applied to the cable from one or two terminals and are usually used as a preliminary step of fault location, such as capacitance method, bridge technique and earth gradient method. After finding the approximate location of the fault, tracer methods are used to get the exact location such as tracing current methods and thumper acoustic method. Acoustic involves a capacitor discharge through the cables with utility personnel having headphone sensors listing for the noise associated to the arcing in the cables. The applied voltage and current in such methods are so large that they may cause additional damage to the cables. All the above technique requires the cable to be taken out of service and is not able to detect inception faults or partial discharge.This thesis studies the on line methods, fault location are solved by processing, recorded information of fault current and voltage. This information is analyzed through Teleflex screen to get fault location and repairing it in small time to improve power quality. Avery large lengths of LV and MV cables are distributed in Cairo region. Cables networks are very complicated and there aren’t any clear maps for these cables networks.These cables are subjected to various faults. The fault location in Cairo cables network is complex, difficult, time consuming and labor intensive. Consequently the cables fault location technique with high degree of accuracy and a high degree of efficiency is increasingly demanded with the increased importance of these underground cables. This thesis discusses the problem encountered in cables jointing of Egyptian distribution network, especially in great Cairo region cable network.