• Offset mho circle for Z1
• Offset mho circle for Z2
• Directional blinder
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 120: 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
120.
In LEXPDIS function the zone measurement is done as shown in figure 121.
Section 7 1MRK502052-UEN B
Impedance protection
276
Technical manual
To Next Page
Loading...
