Emax Low voltage air circuit-breakers - ABB Download Center

Direction (OUT-IN)Bw ➞ BwBw ➞ FwFw ➞ FwReference DirectionArrow2) in the case of a fault in B, circuit-breaker QF2 is passed through by a current from busbar B1;this current flows in a direction discordant with the one set. The OUT Bw bus of QF2 “blocks”the IN Fw bus of circuit-breaker QF1 and the IN Bw bus of circuit-breaker QF3: in fact, thecurrent flows through QF1 inQF1 +PR123AG1I>INFw BwOUTFw BwQF2 +PR123BG2I>INFw BwOUTFw Bwthe same direction as the setting,whereas QF3 is passedthrough by a current discordantwith the setting (the active“block” signals are indicatedby wider arrows).CB1QF3 +PR123I>INFw BwOUTFw BwDM1SDC200192F0001Direction (OUT-IN)Bw ➞ BwBw ➞ FwFw ➞ FwReference DirectionArrow3) in case of a fault in C, circuit-breakers QF1 and QF2 are passed through by a current flowingin the same direction as the one set, whereas QF3 is passed through by a current with discordantdirection. No circuitbreakeris “blocked” and consequentlyG1G2all the circuit-break-ABers affected by the fault willtrip according to the time settingsof protections “S” and/or “I”.QF1 +PR123I>INFw BwOUTFw BwQF2 +PR123I>INFw BwOUTFw Bw6CB1QF3 +PR123I>INFw BwOUTFw BwDM1SDC200193F0001ABB SACE 6/17