Measurement Voltage Failure Detection - Siemens SIPROTEC 4 User Manual

Phase Sequence of Voltage and Current
To detect swapped phase connections in the voltage and current input circuits, the phase sequence of the
phase-to-phase measured voltages and the phase currents are checked by monitoring the sequence of same
polarity zero crossing of the voltages.
Direction measurement with normal voltages, path selection for fault location, and negative sequence detec-
tion all assume a phase sequence of "abc". Phase rotation of measurement quantities is checked by verifying
the phase sequences. For that purpose, the phase-sequence monitoring uses the phase-to-phase voltages V
V , V .
B3 C1
Voltages: V before V
A2
Currents: Ι before Ι
A
Verification of the voltage phase rotation is done when each measured voltage is at least
|V |, |V |, |V | > 40 V
A2 B3 C1
Verification of the current phase rotation is done when each measured current is at least:
|Ι |, |Ι |, |Ι | > 0,5 Ι
A B C
For abnormal phase sequences, the messages
with the switching of this message
For applications in which an opposite phase sequence is expected, the protective relay should be adjusted via
a binary input or the respective parameter PHASE SEQ. (address 209). If the phase sequence is changed in
the relay, 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.
2.12.1.6

Measurement Voltage Failure Detection

Requirements
The measurement voltage failure detection function, referred to as "Fuse Failure Monitor" (FFM), only oper-
ates if 3 phase-to-ground voltages are connected.
With phase-to-phase voltages and U
Purpose of the Fuse Failure Monitor
In case of a measuring voltage failure caused by a fault or a broken wire in the voltage transformer secondary
system, a zero voltage can be simulated to individual measuring loops.
The displacement voltage element of the sensitive ground fault detection, the directional overcurrent protec-
tion, the voltage-controlled inverse time non-directional overcurrent protection, the undervoltage protection
and the synchronization function in the 7SJ64 can thereby acquire incorrect measuring results.
The blocking of this function by the FFM is configurable.
The displacement voltage element of the (sensitive) ground fault detection, the time overcurrent protection
ground and the undervoltage protection can thereby obtain incorrect measuring results.
Mode of Operation – Grounded System
The device is informed of the application of the FFM in a grounded system via address 5301 FUSE FAIL
MON. Solid grounded.
NOTE
i
i
On systems where the ground fault current is very small or absent (e.g. ungrounded supply transformers),
fuse failure monitoring must be disabled or set to Coil.gnd./isol..
The logic diagram on the operating mode in a grounded system is illustrated in
configuration and MLFB, the FFM operates with measured or calculated values V
voltage occurs without a ground fault current being registered simultaneously, then there is an asymmetrical
fault in the secondary circuit of the voltage transformer.
SIPROTEC 4, 7SJ62/64, Manual
C53000-G1140-C207-8, Edition 08.2016
vor V and
B3 C1
before Ι .
B C
.
N
Fail Ph. Seq. .
2.23.2 Setting
or single-phase connection, the function is disabled.
N
Fail Ph. Seq. V or Fail Ph. Seq. I are issued, along
Notes). The phase-related messages, malfunction
Functions
2.12 Monitoring Functions
Figure 2-73. Depending on the
or Ι . If zero sequence
N N
,
A2
185