ABB RELION REX640 Technical Manual page 874

Section 4
Protection functions
868
resistive and reactive reaches. The underimpedance method is supervised by a load
encroachment logic which ensures that the load impedance does not interfere with the
faulted phase selection.
The "OC AND Und impedance" method combines "Overcurrent" and "Under
impedance" methods so that both criteria have to be fulfilled.
All phase selection methods require that all three phase currents are measured and all
three phase-to-earth voltages are available. If only phase-to-phase voltages are
available (Phase voltage Meas = "Ph-to-ph without Uo"), only phase-to-phase
measuring loops can be released for measurement. The release of phase-to-earth fault
measuring elements is then blocked, RELEASE_PE = "No fault".
The operation of the faulted phase selection function is highly dependent on the earth-
fault detection function. The phase preference or faulted loop selection logic can be set
to filter the faulted phases to be released for measurement in the protection zones.
The general indication of a fault is given in the binary output START_GFC. The
faulted phase information can be found from the integer monitored data signal
STARTS_GFC.
Table 831: Enumeration values for integer monitored data signal STARTS_GFC
Enumerator name
No fault
AG Fault
BG Fault
CG Fault
AB Fault
BC Fault
CA Fault
ABC Fault
The fault loops released for measurement are indicated with the integer monitored
data signals RELEASE_PE and RELEASE_PP. These signals may be filtered by the
phase preference of the faulted loop selection logic.
Table 832: Enumeration values for integer monitored data signal RELEASE_PE
Enumerator name
No fault
AG Fault
BG Fault
CG Fault
AB Fault
BC Fault
CA Fault
ABC Fault
Value
-5
1
2
3
4
5
6
7
Value
-5
1
2
3
4
5
6
7
1MRS759142 C
REX640
Technical Manual