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
Section 20 1MRK 505 370-UEN D
Basic IED functions
438 Busbar protection REB670
Application manual
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