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Phase sequence of the voltages
To detect swapped phase connections in the voltage input circuits, the direction of rotation of the phase-
tophase voltages is checked. Therefore the sequence of the zero crossings of the currents (having the same
sign) is checked.
Phase rotation of measurement quantities is checked by verifying the phase sequences. Here, the phase
sequence supervision requires the phase-phase voltages V
Voltages: V
before V
A2
Verification of the voltage phase rotation is done when each measured voltage is at least
|V
|, |V
|, |V
| > 40 V.
A2
B3
C1
For abnormal phase sequences, the messages
this message
Fail Ph. Seq. .
For applications in which an opposite phase sequence is expected, the protective relay should be adjusted via
a binary input or a programmable setting PHASE SEQ. (Addresse 209). If the phase sequence is changed in
the device, phases B and C internal to the relay are reversed, and the positive and negative sequence currents
are thereby exchanged (see also Section
values, and measured values are not affected by this.
2.5.1.5
Broken Wire Monitoring of Voltage Transformer Circuits
Requirements
The measurement of all three phase-to-ground voltages is a requirement for the functionality. If only two
phaseto- phase voltages were measured, it would not be possible to evaluate two of the required criteria.
Task
The "Broken Wire" monitoring function monitors the voltage transformer circuits of the secondary system with
regard to failure. One distinguishes between single-phase and two-phase failures.
Mode of Operation / Logic
All three phase-to-ground voltages, the displacement voltage and the displacement voltage are measured. The
required values are calculated for the respective criteria and eventually a decision is made. The resulting alarm
message may be delayed. A blocking of the protection functions is however not effected.
The broken wire monitoring is also active during a fault. The function may be enabled or disabled.
The following logic diagram shows how the broken wire monitoring functions.
SIPROTEC 4, 7RW80, Manual
C53000-G1140-C233-4, Edition 07.2018
before V
B3
C1
Fail Ph. Seq. V or are issued, along with the switching of
2.10.2 Setting
, V
, V
.
A2
B3
C1
Notes). The phase-related messages, malfunction
Functions
2.5 Supervision Functions
63
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