8.3.3 Setting guidelines
IP14962-1 v1
8.3.3.1 General
SEMOD55087-5 v7
The settings for Distance measuring zones, quadrilateral characteristic (ZMQPDIS)
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 ZMQPDIS.
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
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-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.The load transfer on the
protected line should be considered for resistive phase to earth faults
• Zero-sequence mutual coupling from parallel lines.
8.3.3.2 Setting of zone 1
SEMOD55087-22 v3
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" 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 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).
8.3.3.3 Setting of overreaching zone
SEMOD55087-26 v6
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.
Section 8 1MRK 506 369-UEN B
Impedance protection
226 Line distance protection REL670 2.2 IEC
Application manual
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