components and so on. This information is then used by the respective functions
connected to this SMAI block in the ACT (for example protection, measurement or
monitoring functions).
21.10.2 Frequency values
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A valid input voltage signal level for frequency measurement can be set with
SMAI setting
MinValFreqMeas in % of UBase. If the input signal level (positive
sequence or single phase voltage) is lower than the MinValFreqMeas level, then the
frequency output is invalid and the connected frequency functions will be blocked.
21.10.3 Setting guidelines
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The parameters for the signal matrix for analog inputs (SMAI) functions are set via
the local HMI or PCM600.
Application functions should be connected to a SMAI block with same task cycle
as the application function, except for e.g. measurement functions that run in slow
cycle tasks.
Negation: If the user wants to negate the 2ph signal, it is possible to choose to
negate only the phase signals Negate2Ph, only the neutral signal NegateN or both
Negate2Ph+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).
A valid input voltage signal level for frequency measurement can be set with
SMAI setting MinValFreqMeas in % of UBase. If the input signal level (positive
sequence or single phase voltage) is lower than the MinValFreqMeas level, then the
frequency output is invalid and the connected frequency functions will be blocked.
Even if the user sets the AnalogInputT
ype 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.
The preprocessing block shall only be used to feed functions within
the same execution cycles. The only exceptions are the
measurement functions (CVMMXN, CMMXU,VMMXU, etc.).
1MRK 506 375-UEN A Section 21
Basic IED functions
Railway application RER670 2.2 IEC 469
Application manual
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