Short Line Application - ABB REG670 Applications Manual

1MRK 502 071-UEN -
8.2.2.4
[1] RLdRv=RLdRvFactor*RLdFw
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual
used on heavy loaded, medium long lines. For short lines, the major concern is to get
sufficient fault resistance coverage. Load encroachment is not a major problem. See
section "Zone reach setting lower than minimum load
X
[1]
RLdRv RLdFw
IEC09000248 V3 EN
Figure 83: Load encroachment phenomena and shaped load encroachment
characteristic
[1]

Short line application

In short line applications, the major concern is to get sufficient fault resistance
coverage. Load encroachment is not such a common problem. The line length that can
be recognized as a short line is not a fixed length; it depends on system parameters
such as voltage and source impedance, see table 25.
Table 25: Definition of short and very short line
Line category Un
110 kV
Very short line 1.1-5.5 km
Short line 5.5-11 km
The IED's ability to set resistive and reactive reach independent for positive and zero
sequence fault loops and individual fault resistance settings for phase-to-phase and
phase-to-earth fault together with load encroachment algorithm improves the
possibility to detect high resistive faults without conflict with the load impedance.
For very short line applications, the underreaching zone 1 can not be used due to the
fact that the voltage drop distribution throughout the line will be too low causing risk
for overreaching.
Z1
ArgLd
R
IEC09000248-3-en.vsdx
Un
500 kV
5-25 km
25-50 km
Section 8
Impedance protection
impedance".
193