Table. 5.3.5 - 54. Register content.
Date and time Event
Fault type
Pre-trigger
current
Fault
current
Pre-fault
current
Trip time
remaining
Used SG
dd.mm.yyyy
hh:mm:ss.mss
Event
name
L1-G…L1-L2-L3 Start/Trip
-20ms current
Start/Trip
current
Start
-200ms
current
0 ms...1800s
Setting
group 1...8
active
5.3.6 Circuit breaker failure protection (CBFP; 50BF/52BF)
The circuit breaker failure protection function is used for monitoring the circuit breaker operation after it
has received a TRIP signal. The function can also be used to retrip a failing breaker; if the retrip fails, an
incomer breaker can be tripped by using the function's CBFP output. The retrip functionality can be
disabled if the breaker does not have two trip coils.
The function can be triggered by the following:
• overcurrent (phase and residual)
• digital output monitor
• digital signal
• any combination of the above-mentioned triggers.
In the current-dependent mode the function constantly measures phase current magnitudes and the
selected residual current. In the signal-dependent mode any of the device's binary signals (trips, starts,
logical signals etc.) can be used to trigger the function. In the digital output-dependent mode the
function monitors the status of the selected output relay control signal. The blocking signal and the
setting group selection control the operating characteristics of the function during normal operation,
i.e. the user or user-defined logic can change function parameters while the function is running.
The circuit breaker failure protection function uses a total of eight (8) separate setting groups which
can be selected from one common source. Additionally, the function's operating mode can be changed
via setting group selection.
The operational logic consists of the following:
• input magnitude processing
• input magnitude selection
• threshold comparator
• block signal check
• time delay characteristics
• output processing.
The inputs of the function are the following:
• operating mode selections
• setting parameters
• digital input signals
• measured and pre-processed current magnitudes.
The function's outputs are CBFP START, RETRIP, CBFP ACT and BLOCKED signals which can be used
for direct I/O controlling and user logic programming. The function generates general time-stamped
ON/OFF events to the common event buffer from each of the two (2) output signals. The time stamp
resolution is 1 ms. The function also provides a resettable cumulative counters for RETRIP, CBFP, CBFP
START and BLOCKED events.
The following figure presents a simplified function block diagram of the circuit breaker failure protection
function.
A
AQ
Q-T256
-T256
Instruction manual
Version: 2.06
64
© Arcteq Relays Ltd
IM00028
Summary of Contents for AQ-T256
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