15.9.2 ApplicationSignal matrix for analog inputs function (SMAI), also known as the preprocessorfunction, processes the analog signals connected to it and gives information about allaspects of the analog signals connected, like the RMS value, phase angle, frequency,harmonic content, sequence components and so on. This information is then used by therespective functions in ACT (for example protection, measurement or monitoring).The SMAI function is used within PCM600 in direct relation with the Signal Matrix toolor the Application Configuration tool.The SMAI function blocks for the 650 series of products are possible to setfor two cycle times either 5 or 20ms. The function blocks connected to aSMAI function block shall always have the same cycle time as the SMAIblock.15.9.3 Setting guidelinesThe parameters for the signal matrix for analog inputs (SMAI) functions are set via thelocal HMI or via the PCM600.Every SMAI function block can receive four analog signals (three phases and one neutralvalue), either voltage or current. SMAI outputs give information about every aspect of the3ph analog signals acquired (phase angle, RMS value, frequency and frequency derivates,and so on – 244 values in total). Besides the block “group name”, the analog inputs type(voltage or current) and the analog input names that can be set directly in ACT.GlobalBaseSel: Selects the global base value group used by the function to define (IBase),(VBase) and (SBase).DFTRefExtOut: Parameter valid only for function block SMAI_20_1:1 andSMAI_20_1:2 .These 2 SMAI blocks can be used as reference blocks for other SMAI blocks; the settingis related to the output signal SPFCOUT, and it defines the source for this output, when theadaptive frequency tracking is used. The possible options are: InternalDFTRef (i.e. fixedDFT reference based on set system frequency): it is not used when the adaptive frequencytracking is needed. DFTRefGrpn (where n is a number from 1 to 12): it define the SMAIblock numbered n, within its task, that is the reference for the adaptive frequency tracking.That reference SMAI shall be voltage type, and shall be connected to a 3-phase voltagetransformer which supply voltage in all the needed operating conditions.ExternalDFTRef : the reference is based on what is connected to input DFTSPFC.DFTReference: Reference DFT for the SMAI block.1MRK 511 286-UUS A Section 15Basic IED functions335Application manual
