100
1.2
14.76
350
350
0
0
0
14.76
100
3.5
3.5
Calculator for earth fault currents when distribution network contains overhead line sections
Distribution Substation dd Primary Substation
Section 1 Section 2 Section 3
Length of Section 0 m 0 m 0 m
Resistance 0.000 Ohms 0.000 Ohms 0.000 Ohms
Reactance 0.000 Ohms 0.000 Ohms 0.000 Ohms
Primary Substation
11kV circuit total impedances
Ground-Mounted
Secondary S/S
Phase To Earth Voltage
6350 Volts
NER T1 NER T2 NER T1 + T2
6.35 Ohms 6.35 Ohms 3.18 Ohms
EPR of Primary
70 Volts
Primary
Earth Grid Resistance
Total Ground Earth Return Current
0.20 Ohms 350 Amps
Distribution Substation dd Primary Substation
dd
11kV Distribution Earth System Arrangement
Measured Soil Resistivity
ohm-metres
Standard substation earth arrangement with
m rods on each corner
Expected resistance of new S/stn grid
ohms
Total Ground return current
Amps
Expected current into local S/S earth grid
Amps
No of connected pole boxes
assuming each is
No. of additional ground mounted s/stns
assuming each is
Resistance of customer's electrode if known
ohms (leave blank if unknown)
Overall Earth Resistance (incl remote earths)
ohms
Assessment of Earth Grid Impedance including vertical earth rods
Input Parameters
Warning some data is copied from another sheet
Soil Resistivity
m
Length of Earth Grid Lgrid
m
Width of Earth Grid Wgrid
m
