الفهرس Only 14 pages are availabe for public view
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Abstract
This report discusses a comparative study for power system grounding.
from many points of view such as the meaning of grounding, the main purposes of grounding system wherever a grounding is the intentional connection of all metal parts of an electrical power system to the earth with a conductor has sufficient current rating to carry any possible fault current.
The reasons for having an earthed system is to provide a sufficiently low impedance path and meansto carry and dissipate electric currents into ground under normal and fault conditions
without exceeding any operating and equipment limits or adversely affecting continuity of service.,
The important of grounding of electrical systems is required for reasons, principally to ensure the safety of people near the system and to prevent damage to the system itself in the event of a fault.
The function of the protective conductor, or earth, is to provide a low resistance path for fault current so that the circuit protective devices operate rapidly to disconnect the supply
The report describes grounded system,ungrounded system, methods of system neutral grounding and effects of current passing through a human body.
Shows sensitive electronic equipment and system to be grounded shus as remote computer units,local area networks (LANs)and Optical Fibers shields.
Use of a phase overcurrent device to detect and clear a ground fault,ground return sensing is only applicable at the source of transformer or generator. Designed of ground fault protection with the over current protection to assure a reliable and well co-ordinated system. Proper grounding of sensitive electronic equipment is essential for safe and proper operation for achieving power quality .Reasons for grounding a power system, personal safety, protective device operation, and noise control.where the most important reason for grounding a device on a power . system is personal safety.
Noise control where noise is defined as unwanted voltages and currents on a grounding system .
• ’It Lightning-protection grounding is essential for the protection of buildings, transmission lines, and electrical equipment from lightning discharges and surges.
,The report discusses a High Voltage Subststions situationswhich can be taken by human subjected to an electric shock and then the ecquivelant circuit has been analized in order to determine the maximum hazardous step and touch voltages that arise during fault situation that may occure for a human, to achieve safe design for the grounding system,we need to review a lot of factors that affect the tolerable step and touch voltagesuch as electrical soil properties,how to choose the conductor ceross section and conductor type. the soil characteristics and the methodes of soil resistivity measuermenls. Finaly the report discuss the steps of designing process program for a grounding ’system of an AC subststion. The program also suggestssome certain modifications for achieve safe grounding design .
computer program written in MA TLAP to aid substation designer in design grounding process.