Earthing Mesh Design 1

[Selva_51]

Hi All,
We are in the midst of designing a hybrid power plant with solar PV, BESS and DG with a 15kV substation (with step up transformer and MV switchgear). For this to prepare a earthing mesh design as per IEEE 80 could you please let me know if I create an individual mesh for the substation, control building and the solar farm and connect all the meshes together in parallel. When I do an individual calculation for Rg,step and touch potential for each of these sections. I observe an attainable Step and touch voltage of more than the system voltage of 480/277V for the control building. Why is this so? and should we calculate the step and touch voltages for the LV side as well? TIA

 

[7anoter4]

The GPR -Ground Potential Rise -it is connected to premises far from the Power Station and only the fault current from an outside station or to an outside station or line which return path is through ground , may rise this potential. So, if a system-480 V, for instance-including power transformer or other power source-and the receiving installations are located entirely on a power station grid the return current of the ground fault occurs through grid and not through ground and doesn't produce GPR.
For Generation Power Station Grounding IEEE 665/1995 standard may help [even it is Withdrawn now!].