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Hilton Mills

Substation Safety: What Will You “Settle” For?

By Conduit

Hilton Mills, HP&D grounding specialist, was presenting at a technical conference about best practices for testing substation grounding systems. During his presentation, he stated that after a ground grid is freshly installed, it will take some time for the voids in the soil to compress, providing a good connection between the ground grid conductors and the soil. Immediately after installation, these voids can cause higher than designed (calculated) impedance, touch, and step values, which should…

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Substation Safety: When “Dirt Cheap” is Bad

By Conduit

Ground Grid Design & Soil Electrical substations are built across the country, comprising a wide range of dimensions and voltages from 4.16kV up to 500kV. These substations are subject to electrical faults, of which 80% are single line to ground (SLG) faults. These fault currents can vary from a few hundred to many thousands of amperes. When designing an electrically safe substation, the cornerstone of any site is the native soil resistivity. Prior to design,…

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