The ST201M-K3 is a single-pole miniature circuit breaker from ABB's ST200M series, designed for supplementary protection according to UL 1077 and CSA C22.2 No. 235 standards. This device features a K-characteristic tripping curve with a rated current of 3.0 A and an interrupt rating up to 10 kA, suitable for both AC and DC applications. The breaker incorporates a thermal release with a conventional non-tripping current of 1.03 × In and conventional tripping current of 1.25 × In, combined with an electromagnetic release providing instantaneous tripping in the range of 20 × In with a response time less than 0.2 seconds. The device operates reliably across ambient temperatures from -40°C to +70°C with appropriate derating factors, features a robust thermoplastic housing, laser-printed product information, and a unique patented twin terminal design for wiring up to 35 mm² with captive screws. The ST201M-K3 is ideal for industrial control panels, motor protection circuits, and equipment requiring selective short-circuit protection with enhanced inrush current tolerance.