ABB RELION Series, Technical Manual

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5.2.3 Functionality
The circuit breaker failure protection 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 retrip function, and also a three-phase conditional
back-up trip function.
CCBRBRF uses the same levels of current detection for both retrip 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 retrip 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 CCBRBRF 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 238: Functional module diagram
Level detector 1
The measured phase currents are compared phasewise to the set Current value . If the
measured value exceeds the set Current value , the level detector reports the exceeding
Section 5
1MRS758755 A
Protection related functions
466 REC615 and RER615
Technical Manual