Protected ObjectLine, transformer, etcForwardReverseDefinition of directionfor directional functionsMeasured quantity ispositive when flowingtowards the objecte.g. P, Q, IReverseForwardDefinition of directionfor directional functionse.g. P, Q, IMeasured quantity ispositive when flowingtowards the objectSet parameterCTStarPointCorrect Setting is"ToObject"Set parameterCTStarPointCorrect Setting is"FromObject"en05000456.vsdIEC05000456 V1 ENFigure 2: Internal convention of the directionality in the IEDIf the settings of the primary CT is correct, that is CTStarPoint set as FromObject orToObject according to the plant condition, then a positive quantity always flowstowards the protected object, and a Forward direction always looks towards theprotected object.The settings of the IED is performed in primary values. The ratios of the main CTs andVTs are therefore basic data for the IED. The user has to set the rated secondary andprimary currents and voltages of the CTs and VTs to provide the IED with their ratedratios.The CT and VT ratio and the name on respective channel is done under Main menu/Hardware/Analog modules in the Parameter Settings tool or on the HMI.3.3 Presumptions for technical dataThe technical data stated in this document are only valid under the followingcircumstances:• CT and VT ratios in the IED are set in accordance with the associated maininstrument transformers. Note that for functions which measure an analoguesignal which do not have corresponding primary quantity, the 1:1 ratio shall be setfor the used analogue inputs on the IED, For example, HZPDIF.• Parameter IBase used by the tested function is set equal to the rated CT primarycurrent.• Parameter UBase used by the tested function is set equal to the rated primaryphase-to-phase voltage.• Parameter SBase used by the tested function is set equal to sqrt(3)* IBase* UBasefor three-phase power system.Section 3 1MRK 504 135-UEN AAnalog inputs44Technical manual
