5) Is a connection made in the Signal Matrix tool (SMT) and Application configuration tool(ACT), which connects the residual/neutral current input to the fourth input channel of thepreprocessing function block 6). Note that this connection in SMT shall not be done if theresidual/neutral current is not connected to the IED.6) Is a Preprocessing block that has the task to digitally filter the connected analog inputs andcalculate:• fundamental frequency phasors for all input channels• harmonic content for all input channels• positive, negative and zero sequence quantities by using the fundamental frequencyphasors of the first three input channels (channel one taken as reference forsequence quantities)These calculated values are then available for all built-in protection and control functionswithin the IED, which are connected to this preprocessing function block in theconfiguration tool. For this application, most of the preprocessing settings can be left to thedefault values.If frequency tracking and compensation is required (this feature is typically required onlyfor IEDs installed in the generating stations), then the setting parameters DFTReferenceshall be set accordingly.4.2.2.6 Example how to connect delta connected three-phase CT set to theIED SEMOD55055-392 v7Figure 14 gives an example how to connect a delta connected three-phase CT set tothe IED. It gives an overview of the required actions by the user in order to makethis measurement available to the built-in protection and control functions in theIED as well.For correct terminal designations, see the connection diagramsvalid for the delivered IED.Section 4 1MRK 504 169-UEN AAnalog inputs48 Transformer protection RET650 2.2 IECApplication manual
