calculate. E.g. at Ph-Ph connection L1, L2 and L3 will be calculated for use in
symmetrical situations. If N component should be used respectively the phase
component during faults I
N
/U
N
must be connected to input 4.
Negation: If the user wants to negate the 3ph signal, it is possible to choose to
negate only the phase signals Negate3Ph, only the neutral signal NegateN or both
Negate3Ph+N. negation means rotation with 180° of the vectors.
GlobalBaseSel: Selects the global base value group used by the function to define
(IBase), (UBase) and (SBase).
MinValFreqMeas: The minimum value of the voltage for which the frequency is
calculated, expressed as percent of UBase (for each instance n).
Settings DFTRefExtOut and DFTReference shall be set to default
value InternalDFTRef if no VT inputs are available.
Even if the user sets the AnalogInputType of a SMAI block to
“Current”, the MinValFreqMeas is still visible. However, using the
current channel values as base for frequency measurement is not
recommendable for a number of reasons, not last among them
being the low level of currents that one can have in normal
operating conditions.
Examples of adaptive frequency tracking
Preprocessing block shall only be used to feed functions within the
same execution cycles (e.g. use preprocessing block with cycle 1 to
feed transformer differential protection). The only exceptions are
measurement functions (CVMMXN, CMMXU,VMMXU, etc.)
which shall be fed by preprocessing blocks with cycle 8.
When two or more preprocessing blocks are used to feed one
protection function (e.g. over-power function GOPPDOP), it is of
outmost importance that parameter setting DFTReference has the
same set value for all of the preprocessing blocks involved
1MRK 511 423-UEN A Section 15
Basic IED functions
Bay control REC650 2.2 IEC 279
Application manual
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