The function has a block input (BLOCK) to block start from the function if required incertain conditions.6.5.3 Setting guidelinesThe parameters for the Phase preference logic function PPLPHIZ are set via the local HMIor PCM600.Phase preference logic function is an intermediate logic between Distanceprotection zone, quadrilateral characteristic function Five zone distanceprotection, quadrilateral characteristic (ZQDPDIS, 21) and Phaseselection with load encroachment, quadrilateral characteristic functionFDPSPDIS (21). Phase selection and zones are set according to normalpraxis, including ground-fault loops, although ground-fault loops willonly be active during a cross-country fault.GlobalBaseSel: Selects the global base value group used by the function to define (IBase),(VBase) and (SBase).OperMode: The operating mode is selected. Choices includes cyclic or acyclic phaseselection in the preferred mode. This setting must be identical for all IEDs in the samegalvanic connected network part.PU27PN: The setting of the phase-to- ground voltage level (phase voltage) which is usedby the evaluation logic to verify that a fault exists in the phase. Normally in a highimpedance grounded system, the voltage drop is big and the setting can typically be set to70% of base voltage (VBase)PU27PP: The setting of the phase-to-phase voltage level (line voltage) which is used bythe evaluation logic to verify that a fault exists in two or more phases. The voltage mustbe set to avoid that a partly healthy phase-to-phase voltage, for example, B-C for a A-Bfault, picks-up and gives an incorrect release of all loops. The setting can typically be 70%of base voltage (VBase) divided by √3, that is 40%.3V0PU: The setting of the residual voltage level (neutral voltage) which is used by theevaluation logic to verify that an ground-fault exists. The setting can typically be 20% ofbase voltage (VBase).Pickup_N: The setting of the residual current level (neutral current) which is used by theevaluation logic to verify that a cross-country fault exists. The setting can typically be20% of base current (IBase) but the setting shall be above the maximum current generatedby the system grounding. Note that the systems are high impedance grounded whichmeans that the ground-fault currents at ground-faults are limited and the occurring INabove this level shows that there exists a two-phase fault on this line and a parallel lineSection 6 1MRK 506 334-UUS AImpedance protection156Application manual
