Is it okay to consider only phase to phase faults for the end of line fault as it produces the minimum fault. Is there any probability of phase to earth or 3 phase faults getting lower than phase to phase faults.
There's certainly a possibility of L-PE faults having lower fault currents than a L-L fault - TT systems being the classic but even in TN systems a reduced c.p.c. or differing material for the c.p.c. (say steel armour rather than copper) will often result in higher impedance and hence lower currents for a L-PE fault. Also L-PE faults are normally driven by a lower voltage than L-L faults (say 230V rather than 400V) so will result in lower current even if the paths have the same impedance.
There's certainly a possibility of L-PE faults having lower fault currents than a L-L fault - TT systems being the classic but even in TN systems a reduced c.p.c. or differing material for the c.p.c. (say steel armour rather than copper) will often result in higher impedance and hence lower currents for a L-PE fault. Also L-PE faults are normally driven by a lower voltage than L-L faults (say 230V rather than 400V) so will result in lower current even if the paths have the same impedance.
