بسم الله الرحمن الرحيم. WELCOOM TO YOU IN THIS PRESENTATION. Substation Grounding. DON BY :. Prepared for : Dr . M. H. Shwehdi. Nasser AL-Harbi. INTRODUCTION. Grounding .
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بسم الله الرحمن الرحيم WELCOOM TO YOU IN THIS PRESENTATION Substation Grounding DON BY : Prepared for : Dr. M. H. Shwehdi Nasser AL-Harbi
INTRODUCTION Grounding The use of electricity brings with it an electric shock hazard for humans and animals, particularly in the case of defective electrical apparatus. In electricity supply systems it is therefore a common practice to connect the system to ground at suitable points. Thus in the event of fault, sufficient current will flow through and operate the protection system, which rapidly isolates the faulty circuit. It is therefore required that the connection to ground to be of sufficiently low resistance. .
Safety and Ground · Basic Problem ·Condition of danager
Design of Grounding System 1. Design Criteria
Design Constants Constant Value Resistivity of Surface Layer ρs (Ω-m) 3000 Time of Current Flow Tc (sec) 1 Length of each ground rod Lr (m) 2.5 Duration of Shock Ts (sec) 0.5 Maximum (fusing) temperature Tm (˚C) 1083 Thermal Capacity Factor TCAP J/(cm³. ˚C) 3.422 Thermal Coefficient of resistivity at Tr αr (1/˚C) 0.00393 Resistivity of Ground conductor ρr at Tr (μ) 1.7241