20.11.1 Application SEMOD55744-4 v10Signal matrix for analog inputs (SMAI), also known as the preprocessor functionblock, analyses the connected four analog signals (three phases and neutral) andcalculates all relevant information from them like the phasor magnitude, phase angle,frequency, true RMS value, harmonics, sequence components and so on. Thisinformation is then used by the respective functions connected to this SMAI block inACT (for example protection, measurement or monitoring functions).20.11.2 Frequency values GUID-B494B93C-B5AA-4FD6-8080-8611C34C2AD8 v5The SMAI function includes a functionality based on the level of positive sequencevoltage, MinValFreqMeas, to validate if the frequency measurement is valid or not. Ifthe positive sequence voltage is lower than MinValFreqMeas, the function freezes thefrequency output value for 500 ms and after that the frequency output is set to thenominal value. A signal is available for the SMAI function to prevent operation due tonon-valid frequency values. MinValFreqMeas is set as % of VBase/√3If SMAI setting ConnectionType is Ph-Ph, at least two of the inputs GRPx_A,GRPx_B and GRPx_C, where 1≤x≤12, must be connected in order to calculate thepositive sequence voltage. Note that phase to phase inputs shall always be connected asfollows: A-B to GRPxA, B-C to GRPxB, C-A to GRPxC. If SMAI settingConnectionType is Ph-N, all three inputs GRPx_A, GRPx_B and GRPx_C must beconnected in order to calculate the positive sequence voltage.If only one phase-phase voltage is available and SMAI setting ConnectionType is Ph-Ph, the user is advised to connect two (not three) of the inputs GRPx_A, GRPx_B andGRPx_C to the same voltage input as shown in figure 212 to make SMAI calculate apositive sequence voltage.SMAI1BLOCKDFTSPFCREVROT^GRP1_A^GRP1_B^GRP1_C^GRP1_NSPFCOUTG1AI3PG1AI1G1AI2G1AI4G1NNEUTRALPHASECPHASEBPHASEAVABSAPTOFV3P*BLOCKBLKTRIPTRIPPICKUPBLKDMAGNFREQTRM_40.CH7(U)SAPTOF(1)_TRIPANSI10000060-1-en.vsdxANSI10000060 V1 EN-USFigure 212: Connection exampleSection 20 1MRK 505 370-UUS ABasic IED functions510 Busbar protection REB670 2.2 ANSIApplication manual
