Grounding calculation

[hafidabdelhalim]

Hello,

I'm working inoil & gas project. I have problem with grounding calculation study ( STEP & Touch voltage) witch fault current to be considered .

for information the substation is composed by :

-Transformer 11/6.6 kV with NER limit current to 300 A &
- Transformer 6.6/0.72 kV direct earthed

EPC Contractor taken the limited current of 300 A as fault current. Is it correct?

What's the best practice.

[luis4170]

As stated in IEEE-80 you need to use the Remote Earth Fault current for the Step and Touch voltage and the Maximum Local Earth Fault current for the sizing of the earth conductor.
It is very clear in IEEE-80.

[hafidabdelhalim]

very thanks