ABB ST201M-B40 DIN Rail Mounted Safety Relay Module

ABB ST201M-B40 is a single-pole DIN-rail mounted miniature circuit breaker in the System Pro M Compact ST200M family, designed to provide overcurrent protection for 40 A circuits in low-voltage installations. It protects 230 V AC lines with a Type B trip characteristic suited to general‑purpose loads, and it carries a rated short‑circuit current of 11.2 kA at 230 VAC (50/60 Hz). The device’s enclosure measures 88 mm high by 17.5 mm wide by 69 mm deep and mounts on a standard 35 mm DIN rail with double-clamped terminals for conductors from 14 AWG to 4 AWG. It is rated for operation from −25°C to 55°C and offers IP20 enclosure protection. The ST201M-B40 is UL 1077 listed for use as a circuit‑protection device in panelboards and control cabinets. Typical applications include protecting feeders and branch circuits in industrial control panels, automation cabinets, and power-distribution enclosures where space is tight and reliable 40 A protection is required. In catalog listings, some variants note a DC rating up to 72 VDC, but the primary specification remains 230 V AC, 40 A, Type B protection.