EQUATION1898 V1 EN-US (Equation 1
12)
and in figure 123
a three phase fault occurs beyond the capacitor
. The resultant IED impedance seen
from the D
B
IED location to the fault may become negative (voltage inversion) until
the spark gap has flashed.
Distance protections of adjacent power lines shown in figure
123 are influenced by this
negative impedance. If the intermediate infeed of short circuit power by other lines is
taken into consideration, the negative voltage drop on X
C
is amplified and a protection
far away from the faulty line can maloperate by its instantaneous operating distance
zone, if no precaution is taken. Impedances seen by distance IEDs on adjacent power
lines are presented by equations 113 to 116.
EQUATION1915 V1 EN-US (Equation 113)
X X
I
I
X X
DA A
F
A
C1 1
1
11
= + ⋅ −
( )
EQUATION1916 V2 EN-US (Equation 114)
X X
I
I
X X
DA A
F
A
C2 2
2
11
= + ⋅ −
( )
EQUATION1917 V2 EN-US (Equation 115)
X X
I
I
X X
DA A
F
A
C3 3
3
11
= + ⋅ −
( )
EQUATION1918 V2 EN-US (Equation 116)
Section 8 1MRK 502 071-UUS A
Impedance protection
260 Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062
Application manual
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