Setting Guidelines - ABB REG670 Applications Manual

1MRK 502 071-UEN -
8.2.3
8.2.3.1
8.2.3.2
8.2.3.3
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual

Setting guidelines

General
The settings for Distance measuring zones, quadrilateral characteristic (ZMFPDIS)
are done in primary values. The instrument transformer ratio that has been set for the
analog input card is used to automatically convert the measured secondary input
signals to primary values used in ZMFPDIS .
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 earth-return compensation factor.
• The effect of infeed between the IED and the fault location, including the
influence of different Z
• The phase impedance of non transposed lines is not identical for all fault loops.
The difference between the impedances for different phase-to-earth 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.
Setting of zone 1
The different errors mentioned earlier usually require a limitation of the
underreaching zone (normally 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"
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 earthed and out of
service and earthed in both ends. The setting of earth-fault reach should be selected to
be <95% also when parallel line is out of service and earthed at both ends (worst case).
Setting of overreaching zone
The first overreaching zone (normally 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 remote end is considerable higher than the fault
current at the IED location.
The setting shall generally not exceed 80% of the following impedances:
/Z ratios of the various sources.
0 1
Section 8
Impedance protection
and select the case(s) that are
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