Functions
2.8 Earth Fault Protection in Earthed Systems (optional)
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
242
Figure 2-117
Power system diagram and symmetrical components for a single-pole earth fault in reverse direction
Z1A, Z2A, Z0A Source impedance side A, symmetrical components
Z1B, Z2B, Z0B Source impedance side B, symmetrical components
ZL, Z0L Line impedance, positive sequence and zero-sequence impedance
ZF
Fault impedance
For the protection of lines whose zero-sequence impedance is significantly higher than the infeed zero-se-
quence impedance (Z
0L
+ Z
0B
> Z
0A
in Figure 2-117), the following setting is recommended for parameter
3186
3U0< forward
:
3U0< forward
= 0,8 *
3I0>
·(lowest directional stage)·* Z
0L
Additional safety can be obtained through the zero-sequence impedance of the infeed at the opposite line end,
which is not taken into account in the formula (Z
0B
in Figure 2-117).
In lines with series compensation, it is possible to compensate the negative influence of the series capacitor
on the directional determination of the earth fault protection. For this purpose, the reactance of the series ca-
pacitor must be entered in parameter
3187
XserCap
. To prevent the compensation from falsifying the direction
measurement in case of reverse faults, the parameter
3187
XserCap
must be set lower or equal to the zero-
sequence reactance of the line.
Содержание SIPROTEC
Страница 20: ...Contents SIPROTEC 7SD5 Manual C53000 G1176 C169 5 Release date 02 2011 20 ...
Страница 351: ...Functions 2 18 Synchronism and Voltage Check optional SIPROTEC 7SD5 Manual C53000 G1176 C169 5 Release date 02 2011 351 ...
Страница 494: ...Functions 2 27 Command Processing SIPROTEC 7SD5 Manual C53000 G1176 C169 5 Release date 02 2011 494 ...
Страница 640: ...Technical Data 4 27 Dimensions SIPROTEC 7SD5 Manual C53000 G1176 C169 5 Release date 02 2011 640 ...
Страница 657: ...Appendix A 2 Terminal Assignments SIPROTEC 7SD5 Manual C53000 G1176 C169 5 Release date 02 2011 657 7SD5 W ...
Страница 754: ...Appendix A 10 Measured Values SIPROTEC 7SD5 Manual C53000 G1176 C169 5 Release date 02 2011 754 ...
Страница 756: ...Literature SIPROTEC 7SD5 Manual C53000 G1176 C169 5 Release date 02 2011 756 ...
Страница 768: ...Glossary SIPROTEC 7SD5 Manual C53000 G1176 C169 5 Release date 02 2011 768 ...