ABB RET650 Technical Manual page 593

1MRK 504 135-UEN A
Technical manual
reference will be used based on the calculated signal frequency from own group.
DFTReference set to External DFT Ref will use reference based on input signal
DFTSPFC.
Settings DFTRefExtOut and DFTReference shall be set to default
value InternalDFTRef if no VT inputs are available. However, if it is
necessary to use frequency adaptive DFT (DFTReference set to other
than default, referring current measuring SMAI) when no voltages are
available, note that the MinValFreqMeas setting is still set in
reference to UBase (of the selected GBASVAL group). This means
that the minimum level for the current amplitude is based on UBase.
For example, if UBase is 20000, the resulting minimum amplitude for
current is 20000 * 10% = 2000.
MinValFreqMeas: The minimum value of the voltage for which the frequency is
calculated, expressed as percent of the voltage in the selected Global Base voltage
group (GBASVAL:n, where 1<n<6).
Below example shows a situation with adaptive frequency tracking with one reference
selected for all instances. In practice each instance can be adapted to the needs of the
actual application.
Section 17
Basic IED functions
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