GE MiCOM P40

The following figure shows the Z
LP
-plane representation of the characteristic:
+R
+jX
Z
replicaphph
ZIV 

-plane
LP
Z
phNZN
IIkZ 
replica
Z
phph
IV
V02732
Figure 55: Impedance Reach line in Z
LP
plane
The Impedance Reach line tilting angle in the Z
LP
plane is fixed at σ (Zx Tilt Top Line setting).
The Impedance Reach line tilting angle in the Z1 plane is defined as follows:
Tilt angle = Ð (Iph/I) + σ = Ð (Iph/(Iph + kZ
N
.IN)) + σ
If the healthy phase currents are much less than the current of the faulty phase, then IN ≈ Iph. The tilting angle in
this case is fixed at the following value:
Tilt angle = Ð ((1/(1 + kZN)) + σ
For products that have mutual compensation, if the mutual compensation is enabled, the tilting angle is:
Tilt angle =
Ð (Iph/(Iph + k
ZN
.IN+ k
ZM
.I
M
)) + σ
The replica reach Z
replica
depends on the ratio of IN/Iph. If IN ≈ Iph (and if mutual compensation is not applied)
then:
Z
replica
=Z (1 + k
ZN
)
So the characteristic is static.
The general characteristic in the Z
LP
plane is shown in the following figure:
P446SV Chapter 7 - Distance Protection
P446SV-TM-EN-1 133