Zone Reach Setting Higher Than Minimum Load Impedance - ABB RELION 650 Series Applications Manual

Section 7
Impedance protection
£
RFPP
EQUATION579 V2 EN-US
Equation
is more than three times as large as the maximum expected load-impedance angle. For other
cases a more accurate calculations are necessary according to equation 75.
£
RFPP 1.6 Z
IECEQUATION2307 V1 EN-US
7.1.3.8

Zone reach setting higher than minimum load impedance

The impedance zones are enabled as soon as the (symmetrical) load impedance crosses the
vertical boundaries defined by
necessary to consider some margin. It is recommended to set
per-phase resistance that corresponds to maximum load.
RLdFw
IECEQUATION2419 V2 EN-US
<
RLdRv
IECEQUATION2420 V2 EN-US
The absolute value of the margin to the closest
at least 0.1 • Z
The load encroachment settings are related to a per-phase load impedance in a symmetrical
star-coupled representation. For symmetrical load or three-phase and phase-to-phase faults,
this corresponds to the per-phase, or positive-sequence, impedance. For a phase-to-earth
fault, it corresponds to the per-loop impedance, including the earth return impedance.
[4] RLdRv=RLdRvFactor*RLdFw
120
×
1.6 Z
load
RFP
74 is applicable only when the loop characteristic angle for the phase-to-phase faults
é
R1
× ê
J
× -
cos
load min
ë
X1
< ×
0.9 R
load min
×
0.9 R
load min
.
load min
ù
J
×
sin
ú
û
[4]
RLdFw and RLdRv
or the lines defined by
ArgLd line should be of the same order, that is,
1MRK 505 363-UEN A
(Equation 74)
(Equation 75)
GUID-78D0227F-2568-4C9A-8921-45812B4ABAF2 v4
ArgLd . So, it is
RLdFw and RLdRv to 90% of the
(Equation 76)
(Equation 77)
Application manual