ABB Relion 670 series - Setting of Overreaching Zone; Setting of Zone 1

input card is used to automatically convert the measured secondary input signals to
primary values used in ZMFCPDIS.
The following basics must be considered, depending on application, when doing the
setting calculations:
• Errors introduced by current and voltage instrument transformers, particularly under
transient conditions.
• Inaccuracies in the line zero-sequence impedance data, and their effect on the
calculated value of the ground-return compensation factor.
• The effect of infeed between the IED and the fault location, including the influence
of different Z
0
/Z
1
ratios of the various sources.
• The phase impedance of non transposed lines is not identical for all fault loops. The
difference between the impedances for different phase-to-ground loops can be as
large as 5-10% of the total line impedance.
• The effect of a load transfer between the IEDs of the protected fault resistance is
considerable, the effect must be recognized.
• Zero-sequence mutual coupling from parallel lines.
8.13.4.2 Setting of zone 1
The different errors mentioned earlier usually require a limitation of the underreaching
zone (zone 1) to 75%...90% of the protected line.
In case of parallel lines, consider the influence of the mutual coupling according to section
"Parallel line application with mutual coupling" and select the case(s) that are valid in the
particular application. By proper setting it is possible to compensate for the cases when the
parallel line is in operation, out of service and not grounded and out of service and
grounded in both ends. The setting of the ground-fault reach should be <85% also when
the parallel line is out of service and grounded at both ends (the worst case).
8.13.4.3 Setting of overreaching zone
The first overreaching zone (zone 2) must detect faults on the whole protected line.
Considering the different errors that might influence the measurement in the same way as
for zone 1, it is necessary to increase the reach of the overreaching zone to at least 120%
of the protected line. The zone 2 reach can be even higher if the fault infeed from adjacent
lines at the remote end is considerably higher than the fault current that comes from behind
of the IED towards the fault.
The setting must not exceed 80% of the following impedances:
1MRK 506 369-UUS - Section 8
Impedance protection
Line distance protection REL670 2.2 ANSI 421
Application manual