125
Breaker failure protection (BFP)
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The breaker-failure protection will be started by a general signal, or in some cases phase
selective signals, either from an external protection, or internally from a protection trip
signal in the terminal.
The breaker receiving the original protection trip command can be retripped from the
BFP. The retrip can be controlled by a current check, or carried out as a direct retrip
without any current check. The direct retrip can be used, because the breaker-to-trip has
already received a tripping command, and the direct retrip does not cause any unselec-
tive tripping
The use of retrip, limits the extent of unwanted power disconnection in case of an acci-
dental start of the BFP at work in the initiating circuits, with the primary circuit in ser-
vice and the load above the set current level.
The back-up trip is sent to the adjacent circuit breakers in order to clear the fault and
disconnect the failing circuit breaker.
Relay
time
30 ms
CB Opening time
40 ms
Normal
CB Opening
Start BFP
Margin
20 ms
<10 ms
BFP
Time
CB Opening time
40 ms
Retrip
original CB
General trip
adjacent CB
110 ms
150 ms
Marginal
20 ms
BFP
time
<10 ms
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Summary of Contents for REO 517
Page 10: ... RQWHQWV ...
Page 16: ...6 Introduction to the application manual KDSWHU QWURGXFWLRQ ...
Page 64: ...54 Blocking of signals during test KDSWHU RPPRQ IXQFWLRQV ...
Page 88: ...78 Scheme communication logic ZCOM KDSWHU LQH LPSHGDQFH ...
Page 146: ...136 Unbalance protection for capacitor banks TOCC KDSWHU XUUHQW ...
Page 166: ...156 Dead line detection DLD KDSWHU 3RZHU V VWHP VXSHUYLVLRQ ...
Page 378: ...368 Monitoring of DC analog measurements KDSWHU 0RQLWRULQJ ...
Page 384: ...374 Pulse counter logic PC KDSWHU 0HWHULQJ ...
Page 412: ...402 Serial communication modules SCM KDSWHU DWD FRPPXQLFDWLRQ ...
Page 440: ...430 LED indication module KDSWHU DUGZDUH PRGXOHV ...