ABB Relion 670 series - Page 415

en06000613.vsd
j
X
R
KC = 0%
KC = 80%
LOC = 0%
KC = 50%
LOC = 50%
j
X
j
X
R R
KC = 2 x 33%
LOC = 33%, 66%
KC = 80%
LOC = 100%
j
X
j
X
R R
IEC06000613 V1 EN
Figure 207: Apparent impedances seen by distance IED for different SC locations
and spark gaps used for overvoltage protection
en06000614_ansi.vsd
MOV protected series capacitor
0 10 20 30 40 50 60
20
10
10
20
0 10 20 30 40 50 60
100
50
50
100
0 10 20 30 40 50 60
20
10
10
20
0 10 20 30 40 50 60
20
10
10
20
Line current as a function of time Capacitor voltage as a function of time
Capacitor current as a function of time MOV current as a function of time
MOV
i
M
i
L
i
C
-jX
C
V
C
ANSI06000614 V1 EN
Figure 208: MOV protected capacitor with examples of capacitor voltage and
corresponding currents
The impedance apparent to distance IED is always reduced for the amount of capacitive
reactance included between the fault and IED point, when the spark gap does not flash
over, as presented for typical cases in figure 89. Here it is necessary to distinguish between
two typical cases:
• Series capacitor only reduces the apparent impedance, but it does not cause wrong
directional measurement. Such cases are presented in figure
89 for 50%
1MRK 506 369-UUS - Section 8
Impedance protection
Line distance protection REL670 2.2 ANSI 409
Application manual