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128
Breaker failure protection (BFP)
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High-
Current
pass
samples
filtering
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The retrip function of the original circuit breaker is set at one of three options:
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Off
function is not executed.
I> check
occurs with a current check.
No I> check
occurs without a current check.
The retrip timer t1 can be set from 0 to 60 s.
A trip pulse, tp, is generated with a length of 150 ms.
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The back-up trip delay timer t2 can be set between 0 and 60 s.
A trip pulse, tp, is generated with a length of 150 ms.
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The breaker failure protection is initiated by the trip commands from the protection
functions, either internal to the terminal or from external commands through binary in-
puts. The start can be initiated by a general signal, or in some cases phase selective sig-
nals.
Creation of
Recti-
stabilizing
fying
signal
RMS
calculation
Decision
through
ASD
comparison
Decision
through
RMS
comparison
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