الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
 |  | from | 201 |  |  |
| | | from | 201 | | |
Abstract
systems made it necessary to develop more efficient,reliable and almost maintenance free protective systems.
t-
This demand, coupled with the very fast development in the electronic integrated circuits, leads to the continuous development of solid state protection devices. Recently progress in the field of digital electronics has resulted in introducing a completely new generation of computer-based protection schemes. The main benefits of these new generation are accuracy, flexibility, easy testing, and mutual-monitoring, self maintenance, simple user interface and programability.
The aim of this thesis is to present a digital impedance relay using a Microprocessor suitable for short T.L with fast tripping characteristic at high accuracy.
The work started by presenting the theory of distance relays and the problems associated with distance relaying. Then the types of distance relays are discussed. Theory of digital relays is explained. The different types of digital algorithms and the selection of the best technique is given. Also, the structure of digital relays is outlined. The realization of digital impedance relay u:;ing the selected