Parameter Setting Guidelines - ABB REG670 Applications Manual

1MRK 502 071-UEN -
8.3.4.10
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual
X
RLdFw
90%
ARGLd
ARGLd
RLdRv
IEC12000176 V2 EN
Figure 132: Load impedance limitation with load encroachment
During the initial current change for phase-to-phase and for phase-to-earth faults,
operation may be allowed also when the apparent impedance of the load
encroachment element is located in the load area. This improves the dependability for
fault at the remote end of the line during high load. Although it is not associated to any
standard event, there is one potentially hazardous situation that should be considered.
Should one phase of a parallel circuit open a single pole, even though there is no fault,
and the load current of that phase increase, there is actually no way of distinguish this
from a real fault with similar characteristics. Should this accidental event be given
precaution, the phase-to-earth reach (RFPEZx) of all instantaneous zones has to be set
below the emergency load for the pole-open situation. Again, this is only for the
application where there is a risk that one breaker pole would open without a preceding
fault. If this never happens, for example when there is no parallel circuit, there is no
need to change any phase-to-earth reach according to the pole-open scenario.

Parameter setting guidelines

IMinOpPEZx and IMinOpPPZx
The ability for a specific loop and zone to issue start or trip is inhibited if the magnitude
of the input current for this loop falls below the threshold value defined by these
settings. The output of a phase-to-earth loop Ln is blocked if ILn < IminOpPEZx. ILn
is the RMS value of the fundamental current in phase Ln.
The output of a phase-to-phase loop LmLn is blocked if ILmLn < IMinOpPPZx.
ILmLn is the RMS value of the vector difference between phase currents Lm and Ln.
Both current limits IMinOpPEZx and IMinOpPPZx are automatically reduced to 75%
of regular set values if the zone is set to operate in reverse direction, that is,
OperationDir=Reverse.
OpModePPZx and OpModePEZx
10%
10% ARGLd
R
ArgLd
Possible
load
Section 8
Impedance protection
X
RLdFw
ARGLd
ARGLd
ARGLd
ARGLd
RLdRv
IEC12000176-2-en.vsd
R
259