ABB Relion 670 series, Technical Reference Manual

Page: 946 / 1232

15.5.2 Principle of operation
The Fault locator (LMBRFLO) in the IED is an essential complement to other
monitoring functions, since it measures and indicates the distance to the fault with high
accuracy.
When calculating distance to fault, pre-fault and fault phasors of currents and voltages
are selected from the Trip value recorder data, thus the analog signals used by the fault
locator must be among those connected to the disturbance report function. The analog
configuration (channel selection) is performed using the parameter setting tool within
PCM600.
The calculation algorithm considers the effect of load currents, double-end infeed and
additional fault resistance.
Z
0m
=Z
0m
+jX
0m
R
1A
+jX
1A
R
0L
+jX
0L
R
1L
+jX
1L
R
0L
+jX
0L
R
1L
+jX
1L
R
1B
+jX
1B
DRPRDRE
LMBRFLO
ANSI05000045_2_en.vsd
ANSI05000045 V2 EN
Figure 468: Simplified network configuration with network data, required for
settings of the fault location-measuring function
If source impedance in the near and far end of the protected line have changed in a
significant manner relative to the set values at fault location calculation time (due to
exceptional switching state in the immediate network, power generation out of order,
and so on), new values can be entered via the local HMI and a recalculation of the
distance to the fault can be ordered using the algorithm described below. It’s also
possible to change fault loop. In this way, a more accurate location of the fault can be
achieved.
The function indicates the distance to the fault as a percentage of the line length, in
kilometers or miles as selected on the local HMI. The fault location is stored as a part
of the disturbance report information (ER, DR, IND, TVR and FL) and managed via
the local HMI or PCM600.
15.5.2.1 Measuring Principle
For transmission lines with voltage sources at both line ends, the effect of double-end
infeed and additional fault resistance must be considered when calculating the distance
Section 15
1MRK505222-UUS C
Monitoring
940
Technical reference manual