P54x/EN OP/La4 Operation
(OP) 5-36
MiCOM P543, P544, P545 & P546
OP
1.11.2 Offset Mho (Distance option only)
If the Zone 3 offset is enabled then it uses no memory polarizing and has a fixed reverse
offset from the origin of a distance polar diagram. Characteristic angle and residual
compensation are as per the forward settings.
1.12 Quadrilateral elements (Distance option only)
The
quadrilateral elements are made from combinations of reactance lines, directional lines
and load blinders.
A counter, similar to that used for the mho element, is incremented when all the relevant
phase comparisons indicate operation. A fast up-count of 6 is issued when the fault is within
80% of the reach of the zone, and well within the resistive reach boundary. Elsewhere, the
increment is always 1 but a fast decrement (6) is used when the faulted phase current is less
than half the minimum operating current setting. Therefore, an area of fast operation for
faults near the characteristic angle is always available, whether mho or quadrilateral
characteristics are applied.
1.12.1 Directional quadrilateral (Distance option only)
T
his characteristic is used for Zones 1, P (optionally reversed), 2 and 4 (reversed).
Reactance
Blinder
Directional
P1172ENb
P1134ENa
Z
jx
R
Figure 19 Quadrilateral characteristics (directional line shown simplified)
(Distance option only)
It is formed from two parallel reactance lines, two parallel resistive reach blinders and
controlled by the delta or conventional directional line. The bottom reactance line (not shown
on Figure 19) and the left hand reach blinder are automatically set to 25% of the re
actance
reach and the right hand blinder, respectively. The reactance line is arranged to operate for
faults below the line, the blinders for faults within the resistive reach limits, and the delta
directional line for forward faults. The counter increments when all of these conditions are
satisfied.
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