Typical substation grounding resistance is between 01

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Unformatted text preview: = 3.2 × 10 m (i.e., a radius of about 1000 m) 0.08 But what the ground lacks in ρ , it makes up for in A! 25 ! Calculation of grounding resistance !  !  !  !  Because of its large cross sectional area the earth is actually a pretty good conductor. Devices are physically grounded by having a conductor in physical contact with the ground; having a fairly large area of contact is important. Most of the resistance associated with establishing an earth ground comes within a short distance of the grounding point. Typical substation grounding resistance is between 0.1 and 1 ohm; fence is also grounded, usually by connecting it to the substation ground grid. 26 ! Calculation of grounding R, cont’d !  Example: Calculate the resistance from a grounding rod out to a radial distance x from the rod, assuming the rod has a...
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