Functions
6-277
7SA6 Manual
C53000-G1176-C156-2
Figure 6-140 Current symmetry monitoring
Broken Conductor
A broken conductor of the protected line or in the current transformer secondary circuit
can be detected, if the minimum current
BALANCE I LIMIT
flows via the feeder. If a
current symmetry failure is detected and the minimum current is below the threshold
PoleOpenCurrent
(address 1130, refer to subsection 6.1.3), an interruption of this
conductor may be assumed. After approximately 5 s the device issues the alarm
“
Fail Conductor
”.
Voltage Symmetry
During normal system operation, a certain degree of voltage symmetry can be as-
sumed. The symmetry is monitored in the device with a magnitude comparison. The
smallest phase voltage is compared to the largest. Non-symmetry is detected when
|U
min
| / |U
max
|
<
BAL. FACTOR U
as long as
|U
max
|
>
BALANCE U-LIMIT
U
max
is the largest and U
min
is the smallest of the three voltages. The symmetry factor
BAL. FACTOR U
provides a measure of the voltage unsymmetry, the threshold value
BALANCE U-LIMIT
defines the lower limit of the operating range for this monitoring
function (refer to Figure 6-141). Both parameters can be set. The reset ratio is approx.
97 %.
This failure is alarmed by “
Fail U balance
”.
Figure 6-141 Voltage symmetry monitoring
I
min
I
N
slope:
I
max
I
N
BALANCE I LIMIT
BAL. FACTOR I
U
min
V
BALANCE U-LIMIT
slope:
BAL. FACTOR U
U
max
V
Содержание siprotec 7SA6
Страница 2: ...Siemens Aktiengesellschaft Book No C53000 G1176 C156 2 ...
Страница 18: ...xviii 7SA6 Manual C53000 G1176 C156 2 ...
Страница 32: ...Introduction 1 14 7SA6 Manual C53000 G1176 C156 2 ...
Страница 82: ...Hardware and Connections 2 50 7SA6 Manual C53000 G1176 C156 2 ...
Страница 119: ...SIPROTEC 4 Devices 4 25 7SA6 Manual C53000 G1176 C156 2 Figure 4 20 CFC Logic example ...
Страница 190: ...Configuration 5 62 7SA6 Manual C53000 G1176 C156 2 ...
Страница 559: ...Control During Operation 7 45 7SA6 Manual C53000 G1176 C156 2 Figure 7 45 Circuit breaker trip test in DIGSI 4 ...
Страница 652: ...Installation and Commissioning 8 78 7SA6 Manual C53000 G1176 C156 2 ...
Страница 724: ...Technical Data 10 56 7SA6 Manual C53000 G1176 C156 ...
Страница 800: ...Appendix A 76 7SA6 Manual C53000 G1176 C156 2 ...
Страница 866: ...Appendix B 66 7SA6 Manual C53000 G1176 C156 2 ...