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Functions
2.10 Monitoring Functions
Figure 2-50
Voltage Symmetry
In healthy network operation it can be expected that the voltages are nearly balanced. Because the phase-to-
phase voltages are insensitive to ground faults, the phase-to-phase voltages are used for the symmetry mon-
itoring. Depending of the connection mode, either the measured quantities or the calculated phase-to-phase
voltages are used. From the phase-to-phase voltages, the rectified average values are generated and checked
for symmetry of their values. The smallest phase voltage is compared with the largest phase voltage.
| V
| / | V
min
max
three voltages and V
allowable asymmetry of the conductor voltages while the limit value BALANCE V-LIMIT (address 8102) is the
lower limit of the operating range of this monitoring (see Figure 2-51). Both parameters can be set. The dropout
ratio is about 97%.
This failure is thus located below the curve for all values and is reported as „Fail V balance".
Figure 2-51
168
Current symmetry monitoring
| < BAL. FACTOR V as long as | V
the smallest. The symmetry factor BAL. FACTOR V (address 8103) represents the
min
Voltage symmetry monitoring
| > BALANCE V-LIMIT. Where V
max
E50417-G1140-C344-A5, Release date 11.2012
is the highest of the
max
SIPROTEC, 7SK80, Manual
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