Some applications require a dedicated circuit breaker protection unit. When the CBFP function is
configured to operate with a digital input signal, it can be used in these applications. When a device is
used for this purpose, the tripping signal is wired to the device's digital input and the device's own
TRIP signal is used only for the CBFP purpose. In this application's incomer the RETRIP and CBFP
signals are also available with different sets of requirements. The RETRIP signal can be used for
tripping the section's feeder breaker and the CBFP signal for tripping the incomer. The following
example does not use retripping and the CBFP signal is used as the incomer trip from the outgoing
breaker trip signal. The TRIP signal can also be transported between different devices by using
GOOSE messages.
Figure. 5.3.6 - 34. Dedicated CBFP operation from digital input signal.
In this mode the CBFP operates only from a digital input signal. Both current and output relay
monitoring can be used. The counter for the CBFP signal begins when the digital input is activated. If
the counter is active until the CBFP counter is used, the device issues a CBFP command to the
incomer breaker. In this application the device tripping signals from all outgoing feeders can be
connected to one, dedicated CBFP device which operates either on current-based protection or on all
possible faults' CBFP protection.
Events and registers
The circuit breaker failure protection function (abbreviated "CBF" in event block names) generates
events and registers from the status changes in RETRIP, in CBFP-activated and CBFP-blocked signals,
as well as in internal pick-up comparators. The user can select which event messages are stored in the
main event buffer: ON, OFF, or both.
The events triggered by the function are recorded with a time stamp and with process data values.
Table. 5.3.6 - 62. Event messages.
Event block name
Event names
CBF1
Start ON
CBF1
Start OFF
CBF1
Retrip ON
CBF1
Retrip OFF
A
AQ
Q-T256
-T256
Instruction manual
Version: 2.06
78
© Arcteq Relays Ltd
IM00028
Summary of Contents for AQ-T256
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