ABB RELION 670 SERIES Applications Manual page 548

Section 9
Current protection
542
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.
t2: Time delay of the back-up trip. The choice of this setting is made as short as possible
at the same time as unwanted operation must be avoided. Typical setting is 90 – 200ms
(also dependent of re-trip timer).
The minimum time delay for the re-trip can be estimated as:
³ + +
t 2 t 1 t t
cbopen BFP reset _
EQUATION1430 V1 EN
where:
t is the maximum opening time for the circuit breaker
cbopen
t is the maximum time for breaker failure protection to detect correct breaker function (the
BFP_reset
current criteria reset)
t is a safety margin
margin
+
t
margin
1MRK 506 369-UUS -
(Equation 483)
Line distance protection REL670 2.2 ANSI
Application manual