Name Type Description
AI4 REAL Analog milliampere input 4
AI5 REAL Analog milliampere input 5
AI6 REAL Analog milliampere input 6
4.12 Signal matrix for analog inputs SMAI
4.12.1 Introduction
Signal matrix for analog inputs function (SMAI), also known as the preprocessor
function, processes the analog signals connected to it and gives information about all
aspects 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
the respective functions in ACT (for example protection, measurement or monitoring).
The SMAI function is used within PCM600 in direct relation with the Signal Matrix
tool or the Application Configuration tool.
4.12.2 Principle of operation
Every Signal matrix for analog inputs function (SMAI) can receive four analog signals
(three phases and one neutral value), either voltage or current, see figure
39 and
figure 40. SMAI outputs give information about every aspect of the 3ph analog signals
acquired (phase angle, RMS value, frequency and frequency derivates etc. – 244 values
in total). The BLOCK input will reset all outputs to 0.
The output signal AI1 to AI4 are direct output of the, in SMT, connected input to
GRPx_A, GRPxB, GRPxC and GRPx_N, x=1-12. AIN is always the neutral current,
calculated residual sum or the signal connected to GRPx_N. Note that function block
will always calculate the residual sum of current/voltage if the input is not connected in
SMT. Applications with a few exceptions shall always be connected to AI3P.
4.12.3 Frequency values
The frequency functions includes a functionality based on level of positive sequence
voltage, IntBlockLevel, to validate if the frequency measurement is valid or not. If
positive sequence voltage is lower than IntBlockLevel the function is blocked.
IntBlockLevel, is set in % of VBase/√3
1MRK505222-UUS C Section 4
Basic IED functions
109
Technical reference manual
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