ABB ST203M-K8 Programmable Industrial Relay Module

ABB ST203M-K8 is a three-pole miniature circuit breaker (MCB) in the ST200M family that provides branch-circuit protection for 400 V AC systems. It is rated 8 A with a Type K thermal-magnetic tripping characteristic, suitable for safeguarding feeders, motors, and general distribution circuits in industrial control panels. The device is DIN-rail mountable on a standard 35 mm rail and uses double-clamp terminals, accepting 0.75–25 mm² multi-wire conductors or 0.75–35 mm² single-wire conductors. Encased in a thermoplastic housing, it carries an IP20 enclosure rating and an operating range of -25 to 55 °C, enabling reliable operation in typical plant environments. Electrical ratings include a rated service voltage of 400 V AC at 50/60 Hz, with short-circuit breaking capacities up to Icu 15 kA at 400 V (Icn 10 kA at 230/400 V). The approximate dimensions are 69 mm long, 52.5 mm wide, and 88 mm high, making it suitable for compact panel layouts. The ST203M-K8 variant delivers the predictable response of a Type K device, providing selective protection in multi-circuit installations and ensuring quick disconnection on severe faults while minimizing nuisance trips in normal operation. This ABB MCB model is part of the ST200M lineup, designed for reliable interchangeability with compatible ABB protection devices in industrial electrical assemblies.