EDR-3000 IM02602003E
Supervision
BF- Breaker Failure [50BF*/62BF]
*=only available in protective relays that offer current measurement.
Available elements:
BF
Principle – General Use
The breaker failure (BF) protection is used to provide backup protection in the event that a breaker fails to operate prop-
erly during fault clearing. This signal is to be used to trip the upstream breaker (e.g. infeed of a busbar) either via an
output relay or via Communication. Depending on the ordered device and type there are different/multiple schemes
available to detect a breaker failure.
Start/Trigger of the BF Timer
A supervision timer »
t-BF«
will be started, once the
BF
module is triggered. Even if the Trigger signal drops again, this
timer will continue to run. If the timer runs down/elapses (is not stopped), the module will issue a trip
afterwords. This trip signal is to be used to trip the upstream breaker (backup).
Stopping the BF
The timer will be stopped if the opening of the breaker is detected. Depending on the supervision scheme the timer will
be stopped if the current falls below the current threshold or if the position signals indicate the open position of the
breaker or a combination of both. The
BF
module will remain within the state rejected until the trigger signal drops (falls
back).
Detecting a Breaker Failure
Depending on the supervision scheme, the Breaker Failure signal (Trip) will be set if either:
the current doesn't fall below the threshold or
the position signals indicate that the breaker is in the closed position or
both.
Reject state of the BF-module
The
BF
module will switch into the rejected state if the Breaker failure triggers are still active while the open position of
the breaker has been detected successfully.
Readiness for Operation
The
BF
module will switch back into the Stand-by if the trigger signals drop (fall back).
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