5.2.3 Functionality
The breaker failure function CCBRBRF is activated by trip commands from the
protection functions. The commands are either internal commands to the terminal
or external commands through binary inputs. The start command is always a
default for three-phase operation. CCBRBRF includes a three-phase conditional or
unconditional re-trip function, and also a three-phase conditional back-up trip
function.
CCBRBRF uses the same levels of current detection for both re-trip and back-up
trip. The operating values of the current measuring elements can be set within a
predefined setting range. The function has two independent timers for trip
purposes: a re-trip timer for the repeated tripping of its own breaker and a back-up
timer for the trip logic operation for upstream breakers. A minimum trip pulse
length can be set independently for the trip output.
The function contains a blocking functionality. It is possible to block the function
outputs, if desired.
5.2.4 Operation principle
The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of the breaker failure protection can be described using a module
diagram. All the modules in the diagram are explained in the next sections. Also
further information on the retrip and backup trip logics is given in sub-module
diagrams.
TRRET
BLOCK
CB_FAULT
TRBU
Back-up
trip
logic
POSCLOSE
START
Io
Retrip
logic
Level
detector
2
Level
detector
1
I_A
I_B
I_C
t
Timer 2
t
Timer 3
CB_FAULT_AL
Start
logic
t
Timer 1
A070445 V3 EN
Figure 285: Functional module diagram. I_A, I_B and I_C represent phase
currents and Io residual current.
Section 5 1YHT530004D05 D
Protection related functions
542 615 series
Technical Manual
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