Settings; Information List; Monitoring; Broken Wire Detection, Fuse Failure Monitoring - Siemens SIPROTEC 4 7UT6 Series Manual

Functions
2.19 Monitoring Functions
2.19.2.3

Settings

Addr. Parameter
8201 TRIP Cir. SUP.
2.19.2.4

Information List

No. Information
6851 >BLOCK TripC
6852 >TripC trip rel
6853 >TripC brk rel.
6861 TripC OFF
6862 TripC BLOCKED
6863 TripC ACTIVE
6864 TripC ProgFail
6865 FAIL: Trip cir.

Monitoring

2.19.3

Broken Wire Detection, Fuse Failure Monitoring

2.19.3.1
Broken Wire
During steady-state operation the broken wire monitoring registers interruptions in the secondary circuit of
the current transformers. In addition to the hazard potential caused by high voltages in the secondary circuit,
this kind of interruption simulates differential currents to the differential protection, such as those evoked by
faults in the protected object.
The broken-wire monitor scans the transient behaviour of the currents of each phase for each measuring loca-
tion. The instantaneous current values are checked for plausibility. If an instantaneous value does not corre-
spond to the expected value although the other steady-state currents continue to flow, a broken wire is
considered. Moreover it is checked, whether the current decays strongly or drops abruptly to 0 (from > 0.1 ·
), or no zero crossing is registered. At the same time, the currents flowing in other phases must not exceed 2
Ι
N
·Ι .
N
The protection functions which react on unsymmetrical currents are blocked as well provided they are
assigned to the defective measuring location: the time overcurrent protection for residual current and the
unbalanced load protection. The device issues the message "Broken wire" indicating also the affected phase
and measuring location.
The blocking is released as soon as a current flow is registered again in the appropriate phase of the device
concerned.
The following figure shows the logic of the wire break detection for 3 measuring locations.
262
Setting Options
ON
OFF
Type of Comments
Informa-
tion
SP >BLOCK Trip circuit supervision
SP >Trip circuit supervision: trip relay
SP >Trip circuit supervision: breaker relay
OUT Trip circuit supervision OFF
OUT Trip circuit supervision is BLOCKED
OUT Trip circuit supervision is ACTIVE
OUT Trip Circuit blk. Bin. input is not set
OUT Failure Trip Circuit
Default Setting Comments
OFF TRIP Circuit Supervision
C53000-G1176-C230-5, Edition 09.2016
SIPROTEC 4, 7UT6x, Manual