GlobalBaseSel: Selects the global base value group used by the function to define (IBase),
(VBase) and (SBase).
MinValFreqMeas: The minimum value of the voltage for which the frequency is
calculated, expressed as percent of VBase (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
Section 24 1MRK 506 369-UUS -
Basic IED functions
904 Line distance protection REL670 2.2 ANSI
Application manual
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