ABB RELION RET670, Applications Manual

Page: 579 / 1016

RetripMode FunctionMode Description
No CBPos Check Current
re-trip is done without check of
current level
Contact
re-trip is done without check of
auxiliary contact position
Current/Contact
re-trip is done without check of
current level or auxiliary contact
position
BuTripMode : Back-up trip mode is given to state sufficient current criteria to detect
failure to break. For Current operation 2 out of 4 means that at least two currents, of
the three-phase currents and the residual current, shall be high to indicate breaker
failure.
1 out of 3 means that at least one current of the three-phase currents shall be
high to indicate breaker failure. 1 out of 4 means that at least one current of the three-
phase currents or the residual current shall be high to indicate breaker failure. In most
applications
1 out of 3 is sufficient. For Contact operation means back-up trip is done
when circuit breaker is closed (breaker position is used).
Pickup_PH : Current level for detection of breaker failure, set in % of IBase . This
parameter should be set so that faults with small fault current can be detected. The
setting can be chosen in accordance with the most sensitive protection function to start
the breaker failure protection. Typical setting is 10% of
IBase .
Pickup_BlkCont : If any contact based detection of breaker failure is used, this function
can be blocked if any phase current is larger than this setting level. If the
FunctionMode is set Current/Contact breaker failure for high current faults are safely
detected by the current measurement function. To increase security the contact based
function should be disabled for high currents. The setting can be given within the range
5 – 200% of
IBase .
Pickup_N : Residual current level for detection of breaker failure set in % of IBase . In
high impedance grounded systems the residual current at phase- to-ground faults are
normally much smaller than the short circuit currents. In order to detect breaker failure
at single-phase-ground faults in these systems it is necessary to measure the residual
current separately. Also in effectively grounded systems the setting of the ground-fault
current protection can be chosen to relatively low current level. The
BuTripMode is set
1 out of 4 . The current setting should be chosen in accordance to the setting of the
sensitive ground-fault protection. The setting can be given within the range 2 – 200 %
of
IBase .
t1 : Time delay of the re-trip. The setting can be given within the range 0 – 60s in steps
of 0.001 s. Typical setting is 0 – 50ms.
1MRK 504 163-UUS A
Section 9
Current protection
Transformer protection RET670 2.2 ANSI 573
Application manual