ABB RELION REX640 Technical Manual page 524

Protection functions
Figure 302: High-pass filter
Level detector
The harmonics current is compared to the
the value of 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.
524
1.0
0.5
0
0 f 2f
Start value setting, Level detector sends an enabling signal to the
Frequency
Start value setting. If the value exceeds
1MRS759142 F
REX640
Technical Manual