ABB Relion 670 series, Руководство по применению, Страница: 378 / 760

• A fault occurs on a so far healthy power line, over which the power swing has been
detected and the fast distance protection zone has been blocked by ZMRPSB element.
• The power swing occurs over two phases of a protected line during the dead time of a
singlepole auto-reclosing after the Ph-E fault has been correctly cleared by the distance
protection. The second fault can, but does not need to, occur within this time interval.
• Fault on an adjacent line (behind the B substation, see figure 242 ) causes the measured
impedance to enter the operate area of ZMRPSB function and, for example, the zone 2
operating characteristic (see figure 243 ). Correct fault clearance initiates an evolving
power swing so that the locus of the measured impedance continues through zone 1
operating characteristic and causes its unwanted operation, if no preventive measures
have been taken, see figure 243 .
E
A
A B
C
D
F
Z
SA RA
E
C
E
D
xx06000238.vsd
Z
SC
Z
SD
IEC06000238 V1 EN-US
Figure 242: Fault on adjacent line and its clearance causes power swinging between
sources A and C
PSLPSCH function and the basic operating principle of ZMRPSB function operate reliably for
different faults on parallel power lines with detected power swings. It is, however, preferred to
keep the distance protection function blocked in cases of single phase-to-earth faults on so
far healthy lines with detected power swings. In these cases, it is recommended to use an
optionally available directional overcurrent earth-fault protection with scheme communication
logic.
Section 7 1MRK 505 343-UEN B
Impedance protection
372
Application manual