ABB Relion 620 Series - Application

5.7.4.5 Recorded data
All the information required for a later fault analysis is recorded to SCEFRFLO
recorded data. In the protection relay, recorded data is found in Monitoring >
Recorded data > Other protection > SCEFRFLO.
The function has also monitored data values which are used for the read-out
of continuous calculation values. The cross reference table shows which of the
recorded data values are available as continuous monitoring values during a fault.
Table 816: Cross reference table for recorded and monitored data values
Recorded data Monitored data
Flt loop FAULT_LOOP
Flt distance FLT_DISTANCE
Flt Dist quality FLT_DIST_Q
Flt loop resistance RFLOOP
Flt loop reactance XFLOOP
Flt phase reactance XFPHASE
Flt point resistance RF
Flt to Lod Cur ratio IFLT_PER_ILD
Equivalent load Dis S_CALC
XC0F Calc XC0F_CALC
5.7.4.6 Measurement modes
The full operation of SCEFRFLO requires that all three phase-to-earth voltages are
measured. The voltages can be measured with conventional voltage transformers or
voltage dividers connected between the phase and earth ( VT connection is set to
“Wye”). Another alternative is to measure phase-to-phase voltages ( VT connection
is set to “Delta”) and residual voltage (Uo). Both alternatives are covered by setting
the configuration parameter Phase voltage Meas to "Accurate".
When the Phase voltage Meas setting is set to "Ph-to-ph without Uo" and only
phase-to-phase voltages are available (but not Uo), only short-circuit measuring
loops (fault loops “AB Fault”, “BC Fault” or “CA Fault” or “ABC Fault”) can be
measured accurately. In this case, the earth-fault loops (fault loops either “AG
Fault”, “BG Fault” or “CG Fault”) cannot provide correct fault distance estimates
and the triggering of the function in case of earth fault is automatically disabled.
5.7.5 Application
The main objective of the feeder terminals is a fast, selective and reliable operation
in faults inside the protected feeder. In addition, information on the distance to
the fault point is very important for those involved in operation and maintenance.
Reliable information on the fault location greatly decreases the downtime of the
protected feeders and increases the total availability of a power system.
SCEFRFLO provides impedance-based fault location. It is designed for radially
operated distribution systems and is applicable for locating short circuits in all
kinds of distribution networks. Earth faults can be located in effectively earthed
and low resistance/low-reactance earthed networks. Under certain limitations,
Protection related functions
1MRS757644 H
854 620 series
Technical Manual