Earthing arrangement in distribution substations separate three types of eathing.
- Transformer Neutral Earthing
- Surge Arrester Earthing
- MV Line Earthing
Earth resistance should be as low as below specified values.
Transformer Neutral Earthing<35ohms
Surge Arrester Earthing<10ohms
If exceeding above values, then earth resistance should be reduced by having parallel earths as appropriately.
The transformer neutral should be earthed through Cu/PVC or Cu/XLPE cable and connected to the transformer neutral earth point.
Each earthing system is terminated and bonded at Copper bonded earth rod having 17mm diameter and 1.2m length cage.
Surge Arrester Earthing conductor and neutral earthing conductor shall be laid below the ground Also, should be maintained of separate zones between 3m in order to avoid overlapping.
