ABB RELION REX640 Technical Manual page 903

1MRS759142 C
REX640
Technical Manual
checked to see whether a non-zero TLT_ANG_CONFLICT value has been found
although, internally, the polygon boundary has been closed for existing settings.
Directional lines
The direction of a zone is defined with setting Directional mode Znx = "Non-
directional", "Forward" or "Reverse". The directionality of each zone can be set
independently of other zones. For example, zones Z1 and Z2 can be set in the
"Forward" direction and Z3 in the "Reverse"direction. Furthermore, the optionally
supervised earth-fault directional criteria (in low-impedance earthed networks) given
for GFC are checked here together with zone direction criteria fulfilment.
The directionality of a quadrilateral zone is defined with two independent directional
lines. The directional lines can be included into the mho characteristics to secure the
directionality or to transform the non-directional mho characteristic into a directional
one.
The directional lines are adjusted with the Min phase angle zone and Max phase angle
zone settings, which are common for all the zones. The angles are given in degrees.
The directional lines are polarized with the Pol quantity zone method. By default, the
polarization method is positive-sequence voltage ("Pos. seq. volt.").
Directional mode Znx = Forward
X
Min phase angle zone
Forward
GUID-A502A84D-1B3C-436E-9C65-A460C9E1D93C V1 EN
Figure 490: Settings that adjust directional lines in case of quadrilateral
characteristics
The calculated direction of the fault or load (if there is no fault present) current is
indicated in the monitored data DIRECTION = "unknown", "forward", "backward" or
"both". It is important to check setting X1 reverse zone x (or Z1 reverse zone x
reactance part) for quadrilateral directional characteristics (see
corresponding phase-to-earth impedance given in
restrict the negative-reactance reach defined by settings Min Ris Gnd/PP Rch Znx and
Max phase angle zone.
Memory voltage
The memory voltage is based on the healthy positive-sequence voltage stored during
the network healthy state. This fictive voltage is substituted for the measured voltage
with any impedance measurement element polarization if the corresponding voltage
drops too low (limit is 5% Un). Fictive voltage use is indicated by the active monitored
data output VMEM_USED. The polarized impedance direction for a corresponding
Directional mode Znx = Reverse
Max phase angle zone
R
Max phase angle zone
Section 4
Protection functions
X
Reverse
Min phase angle zone
Figure 482
Figure 484) so that it does not
R
and the
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