Hi Hamid, Pls find the answers to your questions item wise: 1-We have an ABB SPAJ142, the earth fault overcurrent is connected to the phase CT’s residual connection. 2-No, it is a notmal Earth Fault O/C 3-In series with relay 4-Just during energizations. 5-Aproximately 35 meters in one case and 50 or so in the second one Thank you for your help.