coupler inputs), the power swing blocking [PS_BLOCK] and the VT supervision [VT_BLOCK]
functions received by the SUPBL segment block all the distance protection functions [DISTBL]
with the exception of the backup overcurrent function.
OR
EXTBLK_DIST
100
PSBBLOCK
VTFAIL
DISTBL
18000019-IEC19000421-1-en.vsdx
IEC19000421 V1 EN-US
Figure 20: SUPBL segment
Table 52: Signals VT SUPBL
Signal
In
Out
Source
Drain
EXTBLK_DIST
X
Binary input: Ext Blk Dist
PSBBLOCK
X
Binary output: Ext Blk PSB
VTFAIL
X
Binary output: VT Sup Delay
DISTBL
X
Binary output: Dist Block
See
.
Switch-onto-fault logic (SOTF)
GUID-73975CBF-96D6-4264-A0C1-21ED47FF37DD v1
When a circuit-breaker is closed onto and existing three-phase fault anywhere in the power
system, instantaneous three-phase tripping takes place.
The fault detectors in this case are the non-directional starters (overcurrent or
underimpedance units) or optionally the over-reaching zone, but this is only used in the
following special cases:
•
Power transformer with high inrush currents at the remote end of the line. In such cases,
fault detection involving the distance measuring units is safer.
•
Close faults with complete voltage collapse may possibly not otherwise be detected, in
which case the parameter
MemDirMode has to be set to Trip.
The switch-onto-fault logic can be activated and the switch-onto-fault signal [SOTF] set to
logical
1 in one of three ways:
1.
by an auxiliary contact on the CB control switch when closing the CB (optocoupler input
Manual close [MANCL_DIST])
2.
by an auxiliary contact on the CB when opening the CB (optocoupler input Dead line
[DEADLINE])
3.
by prolonged undervoltage (U weak) on all three phases and no current enable which
corresponds to a dead line [UWEAK_L1, L2, L3]
Alternative 2) is used, if the VTs are connected to the busbars and alternative 1) is not possible.
The criteria of alternatives 2) and 3) are only effective after either 200 ms or 10 s [SOTF_10S]
(setting), depending on whether the switch-onto-fault logic is required to operate after
1MRK 505 406-UEN B
Section 5
Bay protection functions
Bay protection functions REB500
69
Technical manual
© Copyright 2019 ABB. All rights reserved