ABB RELION REX640 Technical Manual page 496

Section 4
Protection functions
490
1.0
0.5
0
0 f
GUID-784C2760-D2F1-4790-BC1C-558DBD0D6014 V1 EN
Figure 269: High-pass filter
Level detector
The harmonics current is compared to the Start value setting. If the value exceeds the
value of the Start value setting, Level detector sends an enabling signal to the Timer
module.
Current comparison
The maximum of the harmonics currents reported by other parallel feeders in the
substation, that is, in the same busbar, is fed to the function through the I_REF_RES
input. If the locally measured harmonics current is higher than I_REF_RES, the
enabling signal is sent to Timer.
If the locally measured harmonics current is lower than I_REF_RES, the fault is not
in that feeder. The detected situation blocks Timer internally, and simultaneously also
the BLKD_I_REF output is activated.
The module also supervises the communication channel validity which is reported to
the Timer.
Timer
The START output is activated when Level detector sends the enabling signal.
Functionality and the time characteristics depend on the selected value of the Enable
reference use setting.
2f
Frequency
1MRS759142 C
REX640
Technical Manual