ABB Relion 670 Series Applications Manual page 186

Section 8
Current protection
Protection
operate time
The fault
occurs
IEC05000479 V2 EN-US
Figure 89: Time sequence
t2MPh : Time delay of the backup trip at multi-phase start. The critical fault clearance time is
often shorter in case of multi-phase faults, compared to single phase-to-earth faults.
Therefore there is a possibility to reduce the backup trip delay for multi-phase faults. Typical
setting is 90 – 150 ms.
Note that for a protected object which are always tripped three-phase (e.g. transformers,
generators, reactors, cables, etc.) this timer shall always be set to the same value as
t3 : Additional time delay to t2 for a second backup trip TRBU2. In some applications there
might be a requirement to have separated backup trip functions, tripping different backup
circuit breakers.
tCBAlarm : Time delay for alarm in case of indication of faulty circuit breaker. There is a binary
input CBFLT from the circuit breaker. This signal is activated when internal supervision in the
circuit breaker detect that the circuit breaker is unable to clear fault. This could be the case
when gas pressure is low in a SF6 circuit breaker, of others. After the set time an alarm is
given, so that actions can be done to repair the circuit breaker. Note that the time delay for
backup trip
tPulse : Trip pulse duration. This setting must be larger than the opening time of circuit
breakers to be tripped from the breaker failure protection. Typical setting is 200 ms.
tStartTimeout : When one of the two "Follow Modes" is used, there is a settable timer
tStartTimeout which will block the external START input signal when it times-out. This will
automatically also reset the
command. At the same time the STALARM output from the function will have logical value one.
To reset that condition external
prevent unwanted operation of the breaker failure function for cases where a permanent
START signal is given by mistake (e.g.due to a fault in the station battery system). Note that
any backup trip command will inhibit running of
180
Normal t
cbopen
Retrip delay t1 t after re-trip
cbopen
Minimum back-up trip delay t2
Critical fault clearance time for stability
Trip and Start
CCRBRF
t2 is bypassed when the CBFLT is active. Typical setting is 2.0 seconds..
t1 and t2 timers and consequently prevent any backup trip
START signal shall be removed. This is done in order to
© Copyright 2017 Hitachi Power Grids. All rights reserved
t
BFPreset
Margin
IEC05000479_2_en.vsd
tStartTimeout timer.
1MRK 511 401-UEN Rev. K
Time
t2 timer.
Bay control REC670
Application manual