ABB REG670 - Page 284

R
X
Underexcitation Protection
Restrain area
DirAngle
XoffsetDirLine
Z (apparent impedance)
en06000457.vsd
IEC06000457 V1 EN
Figure 122: Impedance constructed as XoffsetDirLine in LEXPDIS protection
LEXPDIS function is schematically described in figure 123.
en06000458-2.vsd
Apparent
impedance
calculation
Positive
sequence
current
phasor
Z
Z in
Z1 char.
Z in
Z2 char.
Dir.
Restrain
³1
Dir.Restrain ON
&
&
startZ1
startZ2 t
t TripZ1
TripZ2
tZ1
tZ2
Positive
sequence
voltage
phasor
IEC06000458 V3 EN
Figure 123: Simplified logic diagram of LEXPDIS protection
Section 7 1MRK502052-UEN B
Impedance protection
278
Technical manual