V02772
Directional zone
Forward direction
Reverse direction
+R
jX
-R
-jX
Directional Line
Directional zone
Offset zone
Figure 63: Quadrilateral Characteristic featuring 2 directional forward zones and 1 offset zone
Directional Quadrilateral Limits
The implementation of Directional Quadrilaterals in this product produces Directional Zone characteristics that are
formed by the combination of five comparators. Each comparator produces a straight line on the complex
impedance plane. The lines produced are:
● Impedance Reach Line
● Reverse Impedance Reach Line
● Resistance Reach Line
● Reverse Resistance Reach Line
● Directional Line.
Each of the lines produced by the comparators defines a tripping limit: Impedance on one side of the line prevents
tripping whereas impedance on the other side of the line may, if the other comparators agree, allow tripping. For
example, impedance beyond the Impedance Reach Line will not allow tripping.
The combination of the comparator outputs produces a polygon shaped tripping region. The polygon may be
either 4-sided or 5-sided. The shape depends according to the settings that are applied by the five comparators
and how the Directional Line interacts with the reach lines (usually the Reverse Impedance Reach Line):
● The Directional Line may completely mask a reach line. If that is the case, the polygon will be 4-sided
(quadrilateral).
● If the Directional Line intersects a reach line, the polygon will be 5-sided.
Creation of a 5-sided polygon is illustrated in the following figure:
Chapter 7 - Distance Protection P543i/P545i
152 P54x1i-TM-EN-1
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