الفهرس 
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Abstract
Earthing plays an important role in the reliability of electrical power systems.
As it helps in ensuring the stability of the voltage level, it is common practice to connect the system to ground at suitable points. Such a connection will absorb sufficient current in the event of fault.
Maintaining variation in the ground grid resistance (Rg) within extremely tight limits is of utmost importance, as substantial variation leads to a potentially large variation in the ground step-voltage in the proximity of operational equipment, and could also increase the touch voltage on the equipment casing.
As such, it is important to monitor the value of (Rg) during operation. All relevant devices currently available manually measure the ground grid resistance (Rg) in-site from time to time.
In this thesis, a monitoring circuit is proposed for continuous measurement of (Rg), so as to detect any hazardous variation in (Rg). The monitoring can either be effected through the control panel or constructed within.the borders of the electrical installation to detect the behavior of (Rg).
In the present thesis, all (Rg) varying factors and typical types of underground noise are extensively studied, and analyzed. Simulation results show the range of each such factor.
Additionally, the prototype device is described in detail, and results of testing it under different operating conditions and Simulation of measuring (Rg) by using matlab software are introduced.
As a measure of evaluation, a comparison in terms of performance between the prototype device and another device of wide market is drawn. The outcome indicates that the proposed device demonstrates exceptional performance and ease of use, in addition to the merits ol monitoring ground grid resistance incessantly.