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BFPBreaker failure protection

1MRK 580 024-BEN

Issued: January 2001Status: New

Data subject to change without notice

Features Adaptive signal detecting algorithm fordetection even during CT saturation

10 ms reset time of current detection ele-

ments during all conditions Phase segregated current measurement

Single or three phase start and retrip

Independent timers for each phase

Three phase backup trip with independent

timer

Application In many protection applications local redun-dancy is used. One part of the fault clearancesystem is however never duplicated, namelythe circuit breaker. Therefor a breaker failureprotection can be used.

The breaker failure protection is initiatedfrom trip signals from protection functionswithin or outside the protection terminal.

When a trip signal is sent to the breaker fail-ure protection first, with no or a very shortdelay, a re-trip signal can be sent to the pro-tected breaker. If fault current is flowingthough the breaker still after a setting time aback-up trip signal is sent to the back-upbreakers. This will ensure fault clearance alsoif the circuit breaker is out of order.

Design The breaker failure protection function is ini-tiated by the trip commands from protectionfunctions placed either inside the same termi-nal or externally, by connection to appropri-ate binary inputs. Three separate functionalinputs are available for single-phase starting.A dedicated input is available also for three-phase starting.

The operate value of the phase segregatedcurrent measuring elements is settable withina wide range. Three independent timers t2 are

available for phase segregated breaker failuredetection.

An additional timer t1 for retrip command isavailable. Dedicated setting allow to enableor disable the retrip or to perform it by cur-rent check or not. Retrip to the faulty circuitbreaker can be issued single phase or threephase.

Special adaptive algorithm (ASD), togetherwith RMS measurement, allow a fast reset-ting time of the current measuring elements.The current measurement is stabilised againstdc-transients which can cause unwanted oper-

ation with saturated current transformers.

Function blockBFP

BLOCK

START

STL1

STL2

STL3

TRBU

TRRET

TRRETL1

TRRETL2

TRRETL3

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Breaker failure protection BFP1MRK 580 024-BEN

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Input and outputsignals

Table 1: Input signals for the breaker failure protection (BFP--) function block

Table 2: Output signals for the breaker failure protection BFP (BFP--) functionblock

Technical data Table 3: Breaker failure protection

Manufacturer

Signal Description

BLOCK Block function

START Start function

STL1 Start phase L1

STL2 Start phase L2

STL3 Start phase L3

Signal Description

TRBU Backup trip

TRRET Retrip

TRRETL1 Retrip by phase L1

TRRETL2 Retrip by phase L2

TRRETL3 Retrip by phase L3

Parameter Setting range Accuracy

Operate current (one mea-

suring element per phase)

5-200% of Ir in steps of 1% +/-2.5% of Ir at I Ir

+/-2.5% of I at I > Ir

Retrip time delay t1 0-60 s in steps of 1 ms +/-0.5% of setting +/-10 ms

Back-up trip time delay t2 0-60 s in steps of 1 ms +/-0.5% of setting +/-10 ms

Parameter Value

Trip operate time Max 18 ms

Reset time Max 10 ms

ABB Automation Products AB

Substation Automation Division

SE-721 59 Vsters

Sweden

Tel: +46 (0) 21 34 20 00

Fax: +46 (0) 21 14 69 18