ABB Relion 670 series - Setting of Zone 1

• 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 terminals of the protected line, the fault
resistance is considerable and the effect must be recognized.
• Zero-sequence mutual coupling from parallel lines.
The setting values of all parameters that belong to ZMHPDIS must correspond to the
parameters of the protected line and be coordinated to the selectivity plan for the network.
Use different setting groups 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. In this way it is
possible to optimize the settings for each system condition.
When Directional impedance element for mho characteristic
(ZDMRDIR, 21D) is used together with Fullscheme distance protection,
mho characteristic (ZMHPDIS) the following settings for parameter
DirEvalType in ZDMRDIR is vital:
• alternative Comparator is strongly recommended
• alternative Imp/Comp should generally not be used
• alternative Impedance should not be used. This alternative is
intended for use together with Distance protection zone, quadrilateral
characteristic (ZMQPDIS)
8.4.3.2 Setting of zone 1
The zone 1 distance elements must be set to underreach a protected circuit to ensure
external fault security.
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
“Setting of zones for parallel line application” and select the case(s) / options that are valid
in the particular application.
1MRK 506 369-UUS - Section 8
Impedance protection
Line distance protection REL670 2.2 ANSI 267
Application manual