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After a settable time (5-100 s) this malfunction is signaled as „Fail I balance"
(no. 163).
Figure 2-81
Voltage Symmetry
In healthy network operation it can be expected that the voltages are nearly balanced.
The monitoring of the measured values in the device checks this balance. The small-
est phase voltage is compared to the largest. Non-symmetry is detected when
U
symmetry factor BAL. FACTOR U (address 2903) represents the allowable asymme-
try of the voltages while the limit value BALANCE U-LIMIT (address 2902) is the
lower limit of the operating range of this monitoring (see Figure 2-82). The dropout
ratio is about 97%.
After a settable time, this malfunction is signaled as „Fail U balance" (no. 167).
Figure 2-82
7SD610 Manual
C53000-G1176-C145-4
Current symmetry monitoring
| < BAL. FACTOR U as long as | U
|U
| / | U
min
max
is the largest of the three phase-to-phase voltages and U
max
Voltage symmetry monitoring
2.15 Monitoring Functions
| > BALANCE U-LIMIT
max
the smallest. The
min
201
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