zone distance protection, mho characteristic (ZQMPDIS, 21) without interfering with theload.The load encroachment algorithm and the blinder functions are always activated in thephase selector. The influence from these functions on the zone measurementcharacteristic has to be activated by switching the setting parameter LoadEnchMode inZQMPDIS (21) for the respective measuring zone(s) to Enabled.6.3.3 Setting guidelinesGlobalBaseSel: Selects the global base value group used by the function to define (IBase),(VBase) and (SBase).INRelPG: The setting of INRelPG for release of the phase-to-ground loop is by default setto 20% of IBase. The default setting is suitable in most applications.The setting must normally be set to at least 10% lower than the setting of 3I0BLK_PPtogive priority to open phase-to-ground loop. INRelPG must be above the normal un-balance current (3I0) that might exist due to un-transposed lines.3I0BLK_PP: The setting of 3I0BLK_PP is by default set to 40% of IBase, which issuitable in most applications.I1LowLevel: The setting of the positive current threshold I1LowLevel used in the sequencebased part of the phase selector for identifying three-phase fault, is by default set to 10% ofIBase.The default setting is suitable in most cases, but must be checked against the minimumthree-phase current that occurs at remote end of the line with reasonable fault resistance.IMaxLoad: The setting IMaxLoad must be set higher than the maximum load currenttransfer during emergency conditions including a safety margin of at least 20%. Thesetting is proposed to be according to equation 66:IMaxLoad =1.2 ILoadEQUATION1614 V2 EN (Equation 66)where:1.2 is the security margin against the load current andILoad is the maximal load current during emergency conditions.The current ILoad can be defined according to equation 67.1MRK 506 334-UUS A Section 6Impedance protection147Application manual
