Toshiba GR200 Series Instruction Manual page 80

Centralized busbar protection ied

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Target CB tripped by CBF re-trip

Figure 2.2-8 shows a CBF re-trip of the target CB. If the OCCBF relay continues to operate a

CBF re-trip command is issued to the target CB if the setting time of [TCBF-RE_CH*] has

elapsed. Unless the CB fails to operate, the OCCBF relay is reset by the CBF re-trip. This may

happen when the CBF function is started by mistake, for example by personnel error during

relay testing, if the bay protection is used to initiate the CBF there is a risk that test personnel

may forget to isolate the start signal to the CBF. If the protection under test trips and there is

sufficient load current flowing through the circuit breaker, there is a risk of a back-trip

command being issued to trip all back-up (adjacent) circuit breakers. This may cause a severe

disturbance. With the re-trip function the consequence of such an error will be limited to the

tripping of only one circuit breaker.

The CBF Zone-trip timer does not time out and the CBF function is reset.

Fault current

Unsuccessful

GEN.TRIP signal

OCCBF_CH* relay

TCB: operating time of the target CB

TOC: reset time of the OCCBF element in CH*

Figure 2.2-8 Timing chart (Target CB tripped by CBF re-trip)

Timer set with [TCBF-RE_CH*]

Timer set with [TCBF-ZONE_CH*]

'OCCBF relay' resets before TCBF-ZONE timer elapses

Centralized GRB200

(Soft: 030, 031, 032, 033, 034)

6F2S1931 (0.20)

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