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 for sequencequantities)These calculated values are then available for all built-in protection and control functions withinthe IED, which are connected to this preprocessing function block in the configuration tool. Forthis application, most of the preprocessing settings can be left to the default values.If frequency tracking and compensation is required (this feature is typically required only forIEDs installed in the generating stations), then the setting parameters DFTReference shall beset accordingly.4.2.2.6 Example how to connect delta connected three-phase CT set to the IEDSEMOD55055-392 v7Figure 24 gives an example how to connect a delta connected three-phase CT set to theIED. It gives an overview of the required actions by the user in order to make thismeasurement available to the built-in protection and control functions in the IED aswell.For correct terminal designations, see the connection diagrams valid forthe delivered IED.1MRK 505 370-UUS A Section 4Analog inputsBusbar protection REB670 2.2 ANSI 79Application manual
