R
X
Underexcitation Protection
Restrain area
Z1, Fast zone
Z2, Slow zone
IEC06000455-2-en.vsd
Underexitation protection
Restrain area
Directional
blinder
R
IEC06000455 V2 EN
Figure 71: Three characteristics in LEXPDIS protection
When the apparent impedance reaches the zone Z1 this zone will operate, normally
with a short delay. The zone is related to the dynamic stability of the generator.
When the apparent impedance reaches the zone Z2 this zone will operate, normally
with a longer delay. The zone is related to the static stability of the generator.
LEXPDIS protection also has a directional blinder (supervision). See figure 71.
In LEXPDIS function the zone measurement is done as shown in figure
72.
1MRK 502 048-UEN A Section 7
Impedance protection
157
Technical manual
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