Current Balance
During normal system operation (i.e. the absence of a fault), symmetry among the input currents is expected.
The symmetry is monitored in the device with a magnitude comparison. The smallest phase current is
compared to the largest phase current. Asymmetry is recognized if:
|
Ι
min
| / |
Ι
max
| <
BAL. FACTOR I
as long as
Ι
max
>
BALANCE I LIMIT
Thereby
Ι
max
is the largest of the three phase currents and
Ι
min
the smallest. The balance factor
BAL. FACTOR
I
(address 2905) represents the permitted imbalance of the phase currents while the limit value
BALANCE I
LIMIT
(address 2904) is the lower limit of the operating range of this monitoring (see
). The
dropout ratio is about 97 %.
After a settable time (5 s - 100 s) this malfunction is signaled as
Fail I balance
“ (no. 163).
[stromsymmetrieueberwachung-020313-kn, 1, en_US]
Figure 2-65
Current symmetry monitoring
Voltage Balance
During healthy system operation, a certain balance of the voltages can be assumed. The monitoring of the
measured values in the device checks this balance. The smallest phase-to-phase voltage is compared to the
largest. Imbalance is recognized if
|V
min
| / |V
max
| <
BAL. FACTOR V
solange |V
max
| >
BALANCE V-LIMIT
Where V
max
being the largest of the 3 phase-to-phase voltages and V
min
the smallest. The balance factor
BAL.
FACTOR V
(address 2903) represents the permitted imbalance of the conductor voltages while the limit value
BALANCE V-LIMIT
(address 2902) is the lower limit of the operating range of this monitoring (see
). The dropout ratio is about 97 %.
After a settable time, this disturbance is signaled with
Fail V balance
(no. 167).
Functions
2.14 Monitoring Functions
SIPROTEC 4, 7SD80, Manual
151
E50417-G1100-C474-A2, Edition 02.2018
Summary of Contents for SIPROTEC 4 7SD80
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