Analog Channel Configuration - ABB RELION REX640 Technical Manual

Section 5
Protection related functions
5.7.4
1096
and in low-resistance or low-reactance earthed networks. With certain limitations,
SCEFRFLO can also be used for locating an earth fault in unearthed distribution
networks. Moreover, SCEFRFLO can be applied to compensated (resonant earthed)
networks where an earth-fault current raising resistor is connected in parallel with the
arc suppression coil. The location of the continuous low-ohmic earth fault can be
determined by using the switching of the parallel resistor of the coil during an earth
fault.
The fault distance calculation is based on the locally measured fundamental frequency
current and voltage phasors. The full operation of SCEFRFLO requires all phase
currents and phase-to-earth voltages to be measured.
The fault distance estimate is obtained when SCEFRFLO is externally or internally
triggered.

Analog channel configuration

SCEFRFLO has three analog group inputs which must be properly configured.
Table 1040: Analog inputs
Input
I3P
U3P
1)
URES
1) Can be connected to GRPOFF if
See the preprocessing function blocks in this document for the
possible signal sources. The GRPOFF signal is available in the
function block called Protection.
There are a few special conditions which must be noted with the configuration.
Table 1041: Special conditions
Condition
U3P connected real measurements
Improper analog channel configuration causes a validation error if the analog
channels are not completely configured or they do not match with certain settings. For
troubleshooting, check the contents of this chapter and also the preprocessing blocks
in this document. The configuration can be written to the protection relay once the
mismatch is corrected.
Description
Three-phase currents
Three-phase voltages
Residual voltage (measured)
Necessary when the phase-to-phase voltages are
measured and
"Accurate"
Phase voltage Meas is set to "Ph-to-ph without Uo"
Description
The function can work with any two phase voltage
channels connected but it is recommended to
connect all three voltage channels.
1MRS759142 C
Phase voltage Meas is set to
REX640
Technical Manual