Figure. 5.4.9. - 54. Retrip and CBFP when selected criteria is current and DO.
In case when the current based protection activates so that either Iset and/or I0Sset current threshold
setting are exceeded the counters for retrip and CBFP are halted until the monitored output contact is
controlled (primary protection operates). From the tripping signal of the primary protection stage the
counters for retrip and CBFP start to calculate the set operating time. The tripping of the primary
protection stage is constantly monitored in this con guration and if the current is not decreased under
the setting limit and the trip signal from primary stage is not reset rst is issued retrip and if the current
is not decreased in time also CBFP will be issued to upstream breaker. If the primary protection
function clears the fault e.g. the circuit breaker operates normally the counters for retrip and CBFP are
reset immediately the current is measured below the threshold settings or the trip signal is reset. This
con guration allows the CBFP to be controlled on current based functions only and other function trips
can be excluded from the CBFP functionality.
AQ-F255
Instruction manual
Version: 2.00
107
© Arcteq Relays Ltd