Figure. 5.4.7. - 37. CBFP when selected criteria is current or DO.
The counter for CBFP starts to calculate the set operating time either from current exceeding the
setting limit or from the primary protection stage trip signal. The tripping of the primary protection stage
is constantly monitored in this con guration regardless of the current status. The pick-up of CBFP is
active until current is not decreased under the setting limit or the trip signal from primary stage is not
reset. In case if either of these conditions are met until the timers set time rst is issued retrip and if
either of the conditions is active also CBFP will be issued to upstream breaker. If the primary protection
function clears the fault e.g. the circuit breaker operates normally the counter for CBFP is reset
immediately the current is measured below the threshold settings and the trip signal is reset. This
con guration allows the CBFP to be controlled on current based functions with added security from the
current monitoring of the CBFP function and other function trips can be also included to the CBFP
functionality.
AQ-T257
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
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