Breaker failure protection (CCRBRF, 50BF) ensures fast back-up tripping of surrounding
breakers in case the protected breaker fails to open. CCRBRF (50BF) can be current
based, contact based, or an adaptive combination of these two conditions.
Current check with extremely short reset time is used as check criterion to achieve high
security against inadvertent operation.
Contact check criteria can be used where the fault current through the breaker is small.
Breaker failure protection, 3-phase activation and output (CCRBRF, 50BF) current
criteria can be fulfilled by one or two phase currents the residual current, or one phase
current plus residual current. When those currents exceed the user defined settings, the
function is triggered. These conditions increase the security of the back-up trip command.
CCRBRF (50BF) function can be programmed to give a three-phase re-trip of the
protected breaker to avoid inadvertent tripping of surrounding breakers.
8.5.3
Function block
ANSI09000272-1-en.vsd
CCRBRF (50BF)
I3P*
BLOCK
BFI_3P
52A_A
52A_B
52A_C
TRBU
TRRET
ANSI09000272 V1 EN
Figure 108:
CCRBRF (50BF) function block
8.5.4
Signals
Table 108:
CCRBRF (50BF) Input signals
Name
Type
Default
Description
I3P
GROUP
SIGNAL
-
Three phase group signal for current inputs
BLOCK
BOOLEAN
0
Block of function
BFI_3P
BOOLEAN
0
Three phase breaker failure initiation
52a_A
BOOLEAN
1
Circuit breaker closed in phase A
52a_B
BOOLEAN
1
Circuit breaker closed in phase B
52a_C
BOOLEAN
1
Circuit breaker closed in phase C
Section 8
1MRK 502 048-UUS A
Current protection
242
Technical manual
