In the DT mode, the function operates after a predefined operate time and resetswhen the fault current disappears. The IDMT mode provides current-dependenttimer characteristics.The function contains a blocking functionality. It is possible to block functionoutputs, timers or the function itself, if desired.4.1.1.4 Operation principleThe function can be enabled and disabled with the Operation setting. Thecorresponding parameter values are "On" and "Off".The operation of three-phase non-directional overcurrent protection can bedescribed by using a module diagram. All the modules in the diagram are explainedin the next sections.A070552 V1 ENFigure 70: Functional module diagram. I_A, I_B and I_C represent phasecurrents.Level detectorThe measured phase currents are compared phasewise to the set Start value. If themeasured value exceeds the set Start value, the level detector reports the exceedingof the value to the phase selection logic. If the ENA_MULT input is active, the Startvalue setting is multiplied by the Start value Mult setting.The IED does not accept the Start value or Start value Mult settingif the product of these settings exceeds the Start value setting range.The start value multiplication is normally done when the inrush detection function(INRPHAR) is connected to the ENA_MULT input.Section 4 1YHT530004D05 DProtection functions140 615 seriesTechnical Manual
