Toshiba GR-200 Series Instruction Manual page 154

Multi functional protection ied

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6F2T0200 (0.15)

Circuit breaker fail protection (CBF)

When a circuit breaker (CB) fails to remove a fault because of the CB failing to open, the

function of circuit breaker fail protection (CBF) is to remove the fault by the back-tripping of

other CBs. For example, if a fault current continues to flow following the issue of a trip

command, the CBF function determines that the CB failure has occurred; the CBF function

will issue another trip command to the adjacent CB(s) and/or the upstream CB.

Although a trip command will have been issued by other protection functions, the CBF

protection has own relay elements and own timers that are used to detect the continuing

presence of a fault following the issuance of the trip command. The relay elements are termed

OCCBF and EFCBF, which run as protection functions within CBF.

GRE200 (1,2)

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Gre200-1 Gre200-2