Toshiba GRL100-701B Instruction Manual page 106

start-up. Tripping of the adjacent breakers can be blocked with the scheme switch [BF2].
There are two kinds of mode of the retrip signal to the original breaker RETRIP: the mode in
which RETRIP is controlled by the overcurrent element OCBF, and the direct trip mode in
which RETRIP is not controlled. The retrip mode together with the trip block can be selected
with the scheme switch [BF1].
Figure 2.11.2 shows a sequence diagram of the BFP when a retrip and backtrip are used. If the
breaker trips normally, the OCBF is reset before timer TBF1 or TBF2 is picked up and the BFP
is reset.
If the OCBF continues operating, a retrip command is given to the original breaker after the
setting time of TBF1. Unless the breaker fails, the OCBF is reset by the retrip. The TBF2 is not
picked up and the BFP is reset. This may happen when the BFP is started by mistake and
unnecessary tripping of the original breaker is unavoidable.
If the original breaker fails, retrip has no effect and the OCBF continues operating and the TBF2
is picked up finally. A trip command CBF-TRIP is issued to the adjacent breakers and the BFP is
completed.
Fault
Start BFP
Adjacent
breakers
Closed
TRIP
Original
breaker
Closed
OCBF
TBF1
RETRIP
TBF2
CBF -
TRIP
Normal trip
Open
T cb Tcb
Toc
TBF1
TBF2
Tcb: operating time of the original breaker
Toc: reset time of the overcurrent element OCBF
Figure 2.11.2 Sequence Diagram
 105 
Trip
Open
Retrip
Open
Toc
6 F 2 S 0 8 5 0