Some features of an earthing system with figure showing details are given.
1. Safest system having separate neutral and protective conductors throughout the system.
2. Does not require earth electrode at site. Earth fault loop impedance is low. Electromagnetic Interference is also low.
1
Unearthed transformer neutral, earthed frame : IT System Earthing.
2
Transformer neutral earthed and frame earthed : TT Earthing system.
3
Transformer neutral earthed, frame connected to neutral : TN-C Earthing system
4
Transformer neutral earthed, frame connected to neutral : TN-S Earthing system