ABB REL650 series, Technical Manual

Page: 164 / 856

a
b
a>b
then c=a
else c=a
c
DeltaIA
DeltaVA
FaultPriority
Adaptive release
dependent on result
from Delta logic
a
b
a<b
then c=b
else c=a
c
OR
AB fault
AG fault
Sequence based
function
OR
3 Phase fault
IA Valid
&
BLOCK
PU_A
en06000386_ansi.vsd
ANSI06000386 V1 EN
Figure 71: Simplified diagram for fault evaluation, phase A
Load encroachment logic
Each of the six measuring loops has its own load (encroachment) characteristic based on
the corresponding loop impedance. The load encroachment functionality is always
activated in faulty phase identification with load encroachment for mho (FMPSPDIS, 21)
function but the influence on the zone measurement can be switched Enabled/Disabledin
the respective Five zone distance protection, mho characteristic (ZMOPDIS) function.
The outline of the characteristic is presented in figure 72 . As illustrated, the resistive reach
in forward and reverse direction and the angle of the sector is the same in all four
quadrants. The reach for the phase selector will be reduced by the load encroachment
function, as shown in figure
72 .
Blinder
Blinder provides a mean to discriminate high load from a fault. The operating
characteristic is illustrated in figure
72 . There are six individual measuring loops with the
blinder functionality. Three phase-to-ground loops which estimate the impedance
according to
Zn = Vph / Iph
and three phase-to-phase loops according to
Zph-ph = Vph-ph / Iph-ph
Section 6
1MRK 506 335-UUS A
Impedance protection
158
Technical manual