11.1.7.3 Dead line detectionA simplified diagram for the functionality is found in figure 113. A dead phasecondition is indicated if both the voltage and the current in one phase is below theirrespective setting values UDLD< and IDLD<. If at least one phase is considered to bedead the output DLD1PH and the internal signal DeadLineDet1Ph is activated. If allthree phases are considered to be dead the output DLD3PH is activatedIL1IL2IL3ab aab aab aIDLD<UL1UL2UL3ab aab aab aUDLD<ORANDANDANDANDAND ANDANDAllCurrLowDeadLineDet1PhDLD3PHDLD1PHintBlockDead Line DetectionIEC10000035-1-en.vsdIEC10000035 V2 ENFigure 113: Simplified logic diagram for Dead Line detection part11.1.7.4 Main logicA simplified diagram for the functionality is found in figure 114. The fuse failuresupervision function (SDDRFUF) can be switched on or off by the setting parameterOperation to On or Off.For increased flexibility and adaptation to system requirements an operation modeselector, OpMode, has been introduced to make it possible to select different operatingmodes for the negative and zero sequence based algorithms. The different operationmodes are:• Off. The negative and zero sequence function is switched off.• UNsINs. Negative sequence is selected.• UZsIZs. Zero sequence is selected.Section 11 1MRK 504 135-UEN ASecondary system supervision250Technical manual
