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Practical guide for ground grid design

Practical guide for ground grid design

Practical guide for ground grid design

(OP)
I'm working on the expansion of an outdoor substation, and I'm looking for a practical guide to design the new earth grid. I have limited information on the existing one. Earth resistivity tests are beeing done now.

Any suggestion on such a practical guide??

It's a 25 kV sub, with 2 txfos (25kV/4kV  & 25kV/600V both resistance grounded), capacitor bank, breakers etc.., the actual fence will be moved about 20 feet out on each side.

Thank you

JL

RE: Practical guide for ground grid design

Hi JLuc
I think you have no problem to calculate the GROUNDING GRID FAULT CURRENT.
In order to build a Grounding Grid and calculate GPR and Touch and Step Potential this link may be useful:
http://www.erico.com/public/library/fep/LT0359.pdf
regards

RE: Practical guide for ground grid design

A classical guides are the IEEE Std 80 for the US and other ANSI market place and CENELEC / IEC Std 479-1 for European countries and other IEC market places.

RE: Practical guide for ground grid design

(OP)
thanks for the suggestions.

the IEEE Std 80 helped a lot. Good "step by step" design procedure.

JL

RE: Practical guide for ground grid design

The problem will be with the unknown existing grid.  For safety in the expansion area, you could assume a minimal grid in the existing substation.  If the expansion increases fault levels at the existing substation, however, you need to check to ensure that the existing substation is safe.  I see two choices.  First, locate the existing grid and ground rods.  Second, install new grid wires and/or ground rods in the existing substation area.  Neither option is easy, particularly in an energized substation.

The CDEGS 2003 Users' Group Conference included a paper on the Assessment of Earthing Systems at Existing Substations by Mark Davies and Matthew Taylor, Strategy & Solutions Ltd, UK.  You might get information on this at the SES website http://www.sestech.com/.  If not, you could contact SES to get a copy.

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