[ ]>pAt s B IxMulti Cin= + ×-æ öç ÷ç ÷ç ÷æ öç ÷ç ÷è øè øEQUATION1261 V2 EN-US (Equation 20)tPRCrvx,tTRCrvx,tCRCrvx: These parameters are used by the customer to create the inversereset time characteristic curve. For more information, refer toTechnical manual.HarmRestrainx: Enables the block of stepx from the harmonic restrain function (2ndharmonic). This function should be used when there is a risk of an unwanted trip caused bypower transformer inrush currents. It can be set toOff/On.6.3 Instantaneous residual overcurrent protection EFPIOCIP14508-1 v36.3.1 IdentificationM14887-1 v4Function description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberInstantaneous residual overcurrentprotectionEFPIOCIN>>IEF V1 EN-US50N6.3.2 Application M12699-3 v5In many applications, when fault current is limited to a defined value by the object impedance,an instantaneous earth-fault protection can provide fast and selective tripping.The Instantaneous residual overcurrent EFPIOC, which can operate in 15 ms (50 Hz nominalsystem frequency) for faults characterized by very high currents, is included in the IED.6.3.3 Setting guidelines IP14985-1 v1M12762-44 v2M12762-4 v4The parameters for the Instantaneous residual overcurrent protection EFPIOC are set via thelocal HMI or PCM600.Some guidelines for the choice of setting parameter for EFPIOC is given.M12762-6 v7GlobalBaseSel: Selects the global base value group used by the function to define (IBase),(UBase) and (SBase).The setting of the function is limited to the operate residual current to the protection (IN>>).The basic requirement is to assure selectivity, that is EFPIOC shall not be allowed to operatefor faults at other objects than the protected object (line).For a normal line in a meshed system single phase-to-earth faults and phase-to-phase-to-earthfaults shall be calculated as shown in figure 33 and figure 34. The residual currents (3I0) to theprotection are calculated. For a fault at the remote line end this fault current is IfB. In thisSection 6 1MRK 505 355-UEN ACurrent protection74Application manual
