According standard IEC 60364 4-41, for TT earthing system the protection must be ensured by RCD, the sensitivity Idn of which complies with the condition Idn<=50V/RA. In TT system, the fault current is limited by earth resistance and is generally well below the setting thresholds of SCPDs and ground fault protection threshold of micrologic 6.
SGR or residual ground fault protection is not convenient as the threshold are high than those recommended in TT.
Below a table giving choice about GFP and RCD relating the level of earth fault value.
Vigirex + toroid for TT earthing system solution would have been a good solution for the rating up to 3200A.
SGR or residual ground fault protection is not convenient as the threshold are high than those recommended in TT.
Below a table giving choice about GFP and RCD relating the level of earth fault value.
Vigirex + toroid for TT earthing system solution would have been a good solution for the rating up to 3200A.
Released for:Schneider Electric South Africa
