BFP Breaker failure protection
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%)3 1MRK 580 139-BEN Page 1 Revision: Issued: December 2002 Data subject to change without notice
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• Adaptive signal detecting algorithm for detection even during CT saturation • 10 ms reset time of current detection elements during all conditions
• Single or two phase start and retrip • Independent timers for each phase • Non-segregated backup trip with independent timer
• Phase segregated current measurement
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In many protection applications local redundancy is used. One part of the fault clearance system is however never duplicated, namely the circuit breaker. Therefore a breaker failure protection can be used. The breaker failure protection is initiated by trip signals from different protection functions within or outside the protection termi-
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nal. When a trip signal is sent to the breaker failure protection first, with no or a very short delay, a re-trip signal can be sent to the protected breaker. If fault current is flowing through the breaker still after a setting time a back-up trip signal is sent to the adjacent breakers. This will ensure fault clearance also if the circuit breaker is out of order.
The breaker failure protection function is initiated by the trip commands from protection functions placed either inside the same terminal or externally, by connection to appropriate binary inputs. A dedicated input is available for general starting.
An additional timer t1 for retrip command is available. Dedicated setting allows to enable or disable the retrip or to perform it by current check or not. Retrip to the faulty circuit breaker can be issued single phase or three phase.
The operate value of the phase segregated current measuring elements is settable within a wide range. Three independent timers t2 are available for phase segregated breaker failure detection.
Special adaptive algorithm (ASD), together with RMS measurement, allow a fast resetting time of the current measuring elements. The current measurement is stabilised against transients which can cause unwanted operation with saturated current transformers.
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BLOCK
Block function
START
Start function
Path in local HMI: ServiceReport/Functions/BreakerFailure/FuncOutputs 7DEOH
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Backup trip
TRRET
Retrip
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Operate current (one measuring element per phase)
5-200% of I1b in steps of 1%
+/- 2.5% of Ir at I ≤ Ir
+/- 7.0 % of Ir at I ≤ Ir
+/- 2.5% of I at I > Ir
+/- 7.0 % of I at I > Ir
Retrip time delay t1
0.000-60.000 s in steps of 1 ms
+/- 0.5 % +/- 10 ms
+/-0.5% +/-10 ms
Back-up trip time delay t2
0.000-60.000 s in steps of 1 ms
+/- 0.5 % +/- 10 ms
+/-0.5% +/-10 ms
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0DQXIDFWXUHU
9DOXH +]
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Trip operate time
Max 18 ms
Max 18 ms
Reset time
Max 10 ms
Max 10 ms
$%%$XWRPDWLRQ7HFKQRORJ\3URGXFWV$% Control & Force Measurement Substation Automation SE-721 59 Västerås Sweden Tel: +46 (0) 21 34 20 00 Fax: +46 (0) 21 14 69 18
%)3 1MRK 580 139-BEN Page 1 Revision: Issued: December 2002 Data subject to change without notice
)HDWXUHV
• Adaptive signal detecting algorithm for detection even during CT saturation • 10 ms reset time of current detection elements during all conditions
• Single or two phase start and retrip • Independent timers for each phase • Non-segregated backup trip with independent timer
• Phase segregated current measurement
$SSOLFDWLRQ
In many protection applications local redundancy is used. One part of the fault clearance system is however never duplicated, namely the circuit breaker. Therefore a breaker failure protection can be used. The breaker failure protection is initiated by trip signals from different protection functions within or outside the protection termi-
'HVLJQ
nal. When a trip signal is sent to the breaker failure protection first, with no or a very short delay, a re-trip signal can be sent to the protected breaker. If fault current is flowing through the breaker still after a setting time a back-up trip signal is sent to the adjacent breakers. This will ensure fault clearance also if the circuit breaker is out of order.
The breaker failure protection function is initiated by the trip commands from protection functions placed either inside the same terminal or externally, by connection to appropriate binary inputs. A dedicated input is available for general starting.
An additional timer t1 for retrip command is available. Dedicated setting allows to enable or disable the retrip or to perform it by current check or not. Retrip to the faulty circuit breaker can be issued single phase or three phase.
The operate value of the phase segregated current measuring elements is settable within a wide range. Three independent timers t2 are available for phase segregated breaker failure detection.
Special adaptive algorithm (ASD), together with RMS measurement, allow a fast resetting time of the current measuring elements. The current measurement is stabilised against transients which can cause unwanted operation with saturated current transformers.
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BLOCK START
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%)3 1MRK 580 139-BEN Page 2
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BLOCK
Block function
START
Start function
Path in local HMI: ServiceReport/Functions/BreakerFailure/FuncOutputs 7DEOH
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Backup trip
TRRET
Retrip
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Operate current (one measuring element per phase)
5-200% of I1b in steps of 1%
+/- 2.5% of Ir at I ≤ Ir
+/- 7.0 % of Ir at I ≤ Ir
+/- 2.5% of I at I > Ir
+/- 7.0 % of I at I > Ir
Retrip time delay t1
0.000-60.000 s in steps of 1 ms
+/- 0.5 % +/- 10 ms
+/-0.5% +/-10 ms
Back-up trip time delay t2
0.000-60.000 s in steps of 1 ms
+/- 0.5 % +/- 10 ms
+/-0.5% +/-10 ms
3DUDPHWHU
0DQXIDFWXUHU
9DOXH +]
+]
Trip operate time
Max 18 ms
Max 18 ms
Reset time
Max 10 ms
Max 10 ms
$%%$XWRPDWLRQ7HFKQRORJ\3URGXFWV$% Control & Force Measurement Substation Automation SE-721 59 Västerås Sweden Tel: +46 (0) 21 34 20 00 Fax: +46 (0) 21 14 69 18
