Answer / zan

Several variable factors are involved in the
design of earthing mat conductor.Therefore, earthing mat
for each substation has to designed individually usually.
The earthing mat has to be designed for the site conditions
to have a low overall impedance and a current carrying
capacity consistent with the fault current magnitude. The
parameter listed below influence the design of earthing mat:
• Magnitude of fault current;
• Duration of fault;
• Soil resistivity .
• Resistivity of surface material;
• Shock duration;
• Material of earthing mat conductor and
• Earthing mat geometry.

Answer / prasad

for bolted joints cross section Area of the conductr
A=0.0013*I*sqrt(t),
for welded joints cross section Area of the conductr
A=0.011*I*sqrt(t),

I - Fault current (KA) = Fault MVA/ (sqrt3 * system KV)
t - Duration of time

Answer / parag shukla

It is basically depends on the soil resistivity & system
load. You can calculate the current for this load from that
calculate the conductor size & earth mat calculations

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