11/29/2023 0 Comments Grounding electrode conductor sizingG58 for: Sph ≤ 16 mm 2 : S PE = S ph 16 35 mm 2 : S PE = S ph / 2 This method is based on PE conductor sizes being related to those of the corresponding circuit phase conductors, assuming that the same conductor material is used in each case. This method is used in practice, therefore, for TT installations, and for dimensioning an earthing conductor The result is sometimes incompatible with the necessity in IT and TN schemes to minimize the impedance of the circuit earth-fault loop, to ensure positive operation by instantaneous overcurrent tripping devices. This method, while being economical and assuring protection of the conductor against overheating, leads to small c.s.a.’s compared to those of the corresponding circuit phase conductors. Adiabatic (which corresponds with that described in IEC 60724).^ Refer to table A.54 of IEC6 or Figure G60 to get values of k factor. ^ 1 2 3 For mechanical reasons, a PEN conductor, shall have a cross-sectional area not less than 10 mm 2 in copper or 16 mm 2 in aluminium.4 mm 2 if the PE is not mechanically protected 2.5 mm 2 if the PE is mechanically protected ^ When the PE conductor is separated from the circuit phase conductors, the following minimum values must be respected:.Otherwise, a correction factor must be applied. ^ Data valid if the prospective conductor is of the same material as the line conductor.Protective conductor between MV/LV transformer and the Main Low Voltage Switchboard (MLVS).Sizing of protective earthing conductor.Connection and choice for protective earthing conductor.Verification of the withstand capabilities of cables under short-circuit conditions.Calculation of minimum levels of short-circuit current.Particular cases of short-circuit current.Short-circuit current supplied by a generator or an inverter.Isc at the receiving end of a feeder as a function of the Isc at its sending end.3-phase short-circuit current (Isc) at any point within a LV installation.Short-circuit current at the secondary terminals of a MV/LV distribution transformer.Calculation of voltage drop in steady load conditions.Sizing of busbar trunking systems (busways).Recommended simplified approach for cable sizing.
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