What the 2CSR255140R1104 is and where it fits
The ABB 2CSR255140R1104 is a residual current breaker (RCCB) from the Molded Case Circuit Breakers sub-category, designed for earth-leakage protection in distribution panels. It sits in the Residual Current Breakers (RCCB/RCBO) category, meaning its primary job is to disconnect the circuit when it detects an imbalance between live and neutral — the classic ground-fault protection function for personnel and equipment.