+R
+jX
V02733
V
ph
/ I
ph
R’
LP
3°
Z’
replica
R
LP
Z
LP
plane
Z
replica
Figure 67: General characteristic in Z
LP
plane
The comparators used for the reactance lines are as per the following table:
Zone Line S1 S2 Condition
Forward or Offset Impedance Reach Vph - Iph.Zreplica Iph∠σ ∠S1 -∠S2 < 0º
Forward or Offset Reverse Impedance Reach Vph - Iph.Z’replica Iph∠-3º ∠S1 -∠S2 > 0º
Reverse Impedance Reach Vph + Iph.Zreplica -Iph∠σ ∠S1 -∠S2 < 0º
Reverse Reverse Impedance Reach Vph + Iph.Z’replica -Iph ∠-3º ∠S1 -∠S2 > 0º
3.2.2.3 EARTH FAULT DYNAMIC REACTANCE LINE TILTING
If you enable dynamic tilting, the reactance lines of the earth-fault Distance Quadrilateral characteristic can
dynamically tilt on the positive sequence impedance (Z1) plane. If the line is polarized with negative sequence
current (I2), the total tilt is made up of the difference between the angle of I2 and the angle of the Distance
protection current (I), plus the user-settable fixed tilt angle σ:
Dynamic Tilt Angle =
∠
(I2 / I) + σ
The default value of the fixed tilt is -3°. It is introduced to reduce the possibility of overreach caused by any small
differences between the negative sequence source impedances, and general CT/VT angle tolerances.
The tilting of Earth-Fault Quadrilateral characteristic reactance lines are constrained to prevent inappropriate
excessive tilting according to the following criteria:
● The Zone 1 Impedance Reach line dynamic tilt can only be applied to bring the Resistive Reach end of the
line towards the +R-axis. This ensures that Zone 1 does not overreach and maintains grading/selectivity
with downstream protection.
● For the other zones (including Zone 1X and Zone 4) the dynamic tilt of the Impedance Reach line can only
act in the sense to prevent underreaching. (This is particularly important for zones used to key channel-
aided distance schemes).
● For Forward operating zones (except Zone 1) the Impedance Reach line dynamic tilt is applied to tilt the
Resistive Reach end of the line away from the +R axis.
Chapter 7 - Distance Protection P543i/P545i
158 P54x1i-TM-EN-1
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