ABB REG650 Technical Manual page 575

Generator protection

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1MRK 502 043-UUS B

Technical Manual

based on the set system frequency. DFTReference set to DFTRefGrpX uses DFT

reference from the selected group block, when own group selected adaptive DFT

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

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 VBase (of the selected GBASVAL group). This means that the

minimum level for the current amplitude is based on VBase. For

example, if VBase 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.

Basic IED functions