+R
+jX
V02723
+Z’
V / I - Z’
V / I
-3°
Figure 72: Reverse impedance reach line construction
For an Offset zone, Z’ is the settable reverse reach. For a directional zone Z’ is a fixed percentage (either 25% or
100%) of the forward reach (Z) in the opposite direction.
The signals provided to the comparator are:
S
1
= V - I.Z’
S
2
= I.
Ð
-3°
Impedance on the tripping side of the Reverse Impedance Reach line is detected when the angle between S1 and
S2 is greater than 0°.
3.3.3
PHASE FAULT RESISTIVE REACH LINE
Refer to the following figure:
Figure 73: Resistive reach of phase elements
Chapter 7 - Distance Protection P543i/P545i
164 P54x1i-TM-EN-1