Functionality - ABB 615 series Technical Manual

1MAC059074-MB A
5.2.3
5.2.4
615 series ANSI
Technical Manual

Functionality

The circuit breaker failure protection function 50BF 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 pickup command is always a default for
three-phase operation. 50BF includes a three-phase conditional or unconditional retrip
function, and also a three-phase conditional back-up trip function.
50BF 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.
Operation principle
The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are "Enable" and "Disable".
The operation of 50BF 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.
I_A
Level
I_B detector
1
I_C
POSCLOSE
PICKUP
Level
IG OR Io detector
2
Timer 3
t
CB_FAULT
BLOCK
GUID-982A97AE-DFE5-4AFF-B894-D12B078F25C4 V1 EN
Figure 388: Functional module diagram
Protection related functions
Timer 1
Start
t
logic
Timer 2
Back-up
t
Section 5
Retrip
TRRET
logic
trip TRBU
logic
CB_FAULT_AL
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