Siemens SIPROTEC Manual page 434

Functions
2.24 Monitoring Functions
Monitoring
Voltage failure, 3-phase
„Fuse Failure Monitor"
Voltage failure, sin-
gle/two-phase
„Fuse Failure Monitor"
Voltage failure,
three-phase
Trip circuit supervision
1)
After three unsuccessful restart attempts, the device is shut down.
2)
DOK = „Device Okay" = Break contact of the readiness relay = Life contact
434
Possible Causes
External
(power system or connection)
External
(voltage transformers)
External
(power system or connection)
External
(trip circuit or control voltage)
Malfunction Re-
sponse
Indication „VT FuseFail>10s"
Distance protection (169),
blocked, „VT FuseFail" (170)
Undervoltage protection
blocked,
Weak-infeed tripping
blocked,
Frequency protection
blocked and
Direction determination
of the earth fault protec-
tion blocked
Indication „VT FuseFail>10s"
Distance protection (169),
blocked „VT FuseFail" (170)
Undervoltage protection
blocked,
Weak-infeed tripping
blocked,
Frequency protection
blocked and
Direction determination
of the earth fault protec-
tion blocked
Indication „Fail U absent" (168)
Distance protection
blocked,
Undervoltage protection
blocked,
Weak-infeed tripping
blocked,
Frequency protection
blocked and
Direction determination
of the earth fault protec-
tion blocked
Indication „FAIL: Trip cir." (6865)
C53000-G1176-C169-5, Release date 02.2011
Indication (No.) Output
As allocated
As allocated
As allocated
As allocated
SIPROTEC, 7SD5, Manual