Question

Three methods on how transformer neutrals can be earthed Commenting on their prospective fault current.

Answer 1

Way of transformer neutral earthing are-

1) Solid earthed system - It is used for LV system with low value of fault current.

2) Resistance earthing system- It is used for HV and LV system with high value of fault current. Solid earthing is not used because high value of fault current will cause tripping of all phase and damage to equipment.

3) Resonant earthing system- In this reactor is used between transformer neutral and station earthing. Best example of it is peteson coil.

It is used in power system if capacitive coupling is high that is large amount of cables are used in transformer.