Current check with extremely short reset time is used as check criterion to achieve high
security against unnecessary 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 unnecessary tripping of surrounding breakers.
7.4.3 Function block
ANSI09000272-1-en.vsd
CCRBRF (50BF)
I3P*
BLOCK
BFI_3P
52A_A
52A_B
52A_C
TRBU
TRRET
ANSI09000272 V1 EN
Figure 43: CCRBRF (50BF) function block
7.4.4 Signals
Table 46: 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
Table 47: CCRBRF (50BF) Output signals
Name
Type Description
TRBU BOOLEAN Back-up trip by breaker failure protection function
TRRET BOOLEAN Retrip by breaker failure protection function
Section 7 1MRK 505 277-UUS C
Current protection
108
Technical Manual
To Next Page
Loading...
