Basler BE1-11m, Instruction Manual, Page: 82 / 610

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Breaker Failure (50BF) Protection BE1-11 m
ReTrip and Trip
The adjustable delay timer allows time for current to clear or the breaker status to transition after signaling
the breaker to trip. The delay timer is initiated when either the 52BFI input or the 50BFI input becomes
true. When both signals are false, the breaker delay timer is stopped.
ReTrip
The ReTrip output is true when the delay timer is actively timing. The delay timer can be stopped by
several methods depending on the timer initiate source. When initiated by a 50BFI signal, the timer is
stopped when current decreases below the pickup setting, when the fast current dropout detector detects
that current has dropped out, or when the control timer expires. When initiated by a 52BFI signal, the
timer is stopped when the BRKSTAT logic element indicates that the breaker is open. Regardless of
initiate method, asserting the Block logic input also stops the timer. In BESTlogic
Plus
, the ReTrip output
can be connected to other logic elements to annunciate the condition, control other elements in logic, and
start the fault recorder (logic element FAULTTRIG).
Trip
The Trip output becomes true when the delay timer expires. In BESTlogic Plus , the Trip output can be
connected to other logic elements and to a physical relay output to annunciate the condition and to initiate
corrective action. If a target is enabled for the element, the BE1-11 m will record a target when the Trip
output becomes true. See the Fault Reporting chapter for more information about target reporting.
Fast Current Detector
The fast current detector directly determines when the current in the poles of the breaker has been
interrupted without having to wait for the fault current samples to clear the one-cycle filter time used by
the normal current measurement function. This function has less than one cycle dropout time.
The fast current detector logic is true if the current has been interrupted and is used to stop the breaker
failure timer. The I=0 algorithm looks at the sample data directly and does not rely upon the 1 cycle
phasor estimation calculation. It rejects dc tail-off by looking for the characteristic exponential decay.
Current is deemed to be interrupted when the current in all three phases is below 5% nominal or if the
current is decaying exponentially. Only the three phase currents are monitored by this function.
CT Source
The CT Source setting configures the breaker failure element to monitor CT circuit 1 or CT circuit 2 on
protection systems equipped with two sets of CTs. CT circuit 1 terminals are designated D1 (IA1) through
D8 (IG1) and CT circuit 2 terminals are designated F1 (IA2) through F8 (IG2). For an illustration, refer to
the Terminals and Connectors chapter.
Programmable Alarm
A Breaker Failure alarm is provided to indicate an alarm condition when the 50BF element trips. The
alarm appears on the front-panel display, web page interface, and on the Alarms metering screen in
BESTCOMS Plus . Refer to the Alarms chapter for information on how to program alarms.
Element Blocking
The Block input provides logic-supervision control of the element. Element blocking is a useful feature to
prevent inadvertent backup tripping during testing.
When true, the Block input disables the element by forcing the Trip and ReTrip outputs to logic 0 and
resetting the element timers. Connect the element Block input to the desired logic in BESTlogic
Plus
.
When the element is initially selected from the Elements view, the default condition of the Block input is a
logic 0.