ABB S203-B25U is a three-pole miniature circuit breaker (MCB) in ABB's S203 family, engineered to protect 3-phase distribution circuits up to 25 A. It is rated for up to 400 V AC and provides a short-circuit breaking capacity of 6 kA, enabling rapid interruption of faults in 3-phase networks. The unit is intended for use in electrical distribution boards and industrial panels, where protection is required on each of the three live conductors in a 3‑phase supply. An alternate catalog number for related configurations is S203MUC-B25.
