Where:1) shows how to connect the secondary side of open delta VT to one VT input inthe IED.+3Uo shall be connected to the IED.2) is TRM where this voltage input is located. It shall be noted that for this voltageinput the following setting values shall be entered:1383 1383VTprim kV= × =EQUATION1928 V1 EN-US (Equation 8)115sec 3 1153VT V= × =EQUATION1929 V1 EN-US (Equation 9)Inside the IED, only the ratio of these two parameters is used. It shall be notedthat the ratio of the entered values exactly corresponds to ratio of oneindividual open delta VT.138138 3115115 3=EQUATION1930 V1 EN-US (Equation 10)3) shows that in this example the first three input channel of the preprocessingblock is not connected in SMT tool.4) shows the connection made in Signal Matrix Tool (SMT), which connect thisvoltage input to the fourth input channel of the preprocessing function block 4).5) preprocessing block has a task to digitally filter the connected analog inputsand calculate:• fundamental frequency phasors for all four input channels• harmonic content for all four input channels• positive, negative and zero sequence quantities by using the fundamentalfrequency phasors for the first three input channels (channel one taken asreference for sequence quantities)These calculated values are then available for all built-in protection and controlfunctions within the IED, which are connected to this preprocessing functionblock in the configuration tool. For this application most of the preprocessingsettings can be left to the default values.If frequency tracking and compensation is required (this feature is typicallyrequired only for IEDs installed in the generating stations) then the settingparametersDFTReference shall be set accordingly.4.2.4.7 Example on how to connect a neutral point VT to the IEDGUID-E0EE34BE-A9B0-4F4F-9C06-BBBE87AD0017 v1Figure 20 gives an example on how to connect a neutral point VT to the IED. This type of VTconnection presents secondary voltage proportional to U0 to the IED.1MRK 505 355-UEN A Section 4Analog inputs53Application manual
