ABB ST203M-D40 (often listed as S203M-D40) is a 3-pole miniature circuit breaker from ABB’s System Pro M Compact family, providing 40 A of overcurrent protection for three-phase circuits. It uses a Type D trip characteristic and offers up to 10 kA interrupting capacity, with North American variants UL 1077 listed and rated for 480Y/277V, while international variants commonly specify 400 V AC operation. The device occupies 3 module widths (3 TE) and is designed for fixed-panel installation in compliant enclosures as part of ABB’s protection and safety portfolio.
