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Functions
2.5 Supervision Functions
If such a malfunction is not cleared by the restart, an additional restart attempt is begun. After three unsuc-
cessful restarts within a 30 second window of time, the device automatically removes itself from service and
the red "Error" LED lights up. The readiness relay drops out and indicates „device malfunction" with its normally
closed contact.
Offset Monitoring
This monitoring function checks all ring buffer data channels for corrupt offset replication of the analog/digital
transformers and the analog input paths using offset filters. Possible offset errors are detected using DC filters,
and the associated sampled values are corrected up to a specific limit. If this limit is exceeded, an indication is
generated (191
values impair the measurements, we recommend sending the device to the OEM plant for corrective action
should this indication persist.
The Offset monitoring can be blocked via the binary input signal
2.5.1.4
Monitoring of the Transformer Circuits
Open circuits or short circuits in the secondary circuits of the voltage transformers, as well as faults in the
connections (important during commissioning!), are detected and reported by the device. The measured
quantities are periodically checked in the background for this purpose, as long as no system fault is present.
Voltage Symmetry
During normal system operation, balance among the voltages is expected. Since the phase-to-phase voltages
are insensitive to ground faults, the phase-to-phase voltages are used for balance monitoring. If the device is
connected to the phase-to-ground voltages, then the phase-to-phase voltages are calculated accordingly,
whereas, if the device is connected to phase-to-phase voltages and the displacement voltage V
phase-to-phase voltage is calculated accordingly. From the phase-to-phase voltages, the device generates the
rectified average values and checks the balance of their absolute values. The smallest phase voltage is
compared with the largest phase voltage.
Asymmetry is recognized if
| V
| / | V
| < BAL. FACTOR V as long as | 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 2-70). Both parameters can be set. The
dropout ratio is about 97%.
This fault is signalled after settable delay time with
[dw_spannungssymmetrieueberwachung, 1, en_US]
Figure 2-13
62
Error Offset ) and integrated into the warning group indication (160). As increased offset
the smallest. The symmetry factor BAL. FACTOR V (address 8103) represents the
min
Voltage symmetry monitoring
>Blk.offset s. (No. 17565).
| > BALANCE V-LIMIT. Where V
max
Fail V balance .
C53000-G1140-C233-4, Edition 07.2018
, then the third
0
is the highest of the
max
SIPROTEC 4, 7RW80, Manual
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