The inner resistive characteristic in the third quadrant outside the load
encroachment zone consist of the sum of the settings R1FInRv and the line
resistance R1LIn. The argument of the tilted lines outside the load encroachment is
the same as the tilted lines in the first quadrant. The distance between the inner and
outer boundary is the same as for the load encroachment in reverse direction, that is
DRv.
7.2.6.3  Reactive reach in forward and reverse direction
M13877-20 v3
The inner characteristic for the reactive reach in forward direction correspond to
the setting parameter X1InFw and the outer boundary is defined as X1InFw + DFw,
where:
DFw = 
RLdOutFw
 - 
KLdRFw
 · 
RLdOutFw
The inner characteristic for the reactive reach in reverse direction correspond to the
setting parameter X1InRv for the inner boundary and the outer boundary is defined
as X1InRv + DRv.
where:
DRv = 
RLdOutRv
 - KLdRRv · 
RLdOutRv
7.2.6.4  Basic detection logic
M13877-24 v7
The operation of the Power swing detection ZMRPSB is only released if the
magnitude of the current is above the setting of the min operating current,
IMinOpPE.
ZMRPSB function can operate in two operating modes:
• The 1 out of 3 operating mode is based on detection of power swing in any of
the three phases. Figure 
67 presents a composition of an internal detection
signal DET-L1 in this particular phase.
• The 2 out of 3 operating mode is based on detection of power swing in at least
two out of three phases. Figure 
68 presents a composition of the detection
signals DET1of3 and DET2of3.
Signals ZOUTLn (outer boundary) and ZINLn (inner boundary) in figure 
67 are
related to the operation of the impedance measuring elements in each phase
separately (n represents the corresponding L1, L2 and L3). They are internal
signals, calculated by ZMRPSB function.
The tP1 timer in figure 
67 serve as detection of initial power swings, which are
usually not as fast as the later swings are. The tP2 timer become activated for the
detection of the consecutive swings, if the measured impedance exit the operate
area and returns within the time delay, set on the tW waiting timer. The upper part
1MRK 505 394-UEN A Section 7
Impedance protection
Line differential protection RED650 2.2 IEC 151
Technical manual