ABB CM-MSS.51S Thermistor motor protection relay - ATEX

The CM-MSS.51S features a wide control-supply range of 24 to 240 V AC/DC, enabling flexible installation across new equipment and retrofits without additional power supplies. Business impact: reduced wiring complexity and lower stocking requirements for spare parts, especially in multi-voltage environments. Application: control circuits in motor drives, conveyors, and machine tools benefit from rapid deployment and consistent protection. The device provides two SPDT outputs (2 x 1 c/o or 1 x 2 c/o) rated to 250 V / 4 A, enabling direct signaling and interlock control to a starter or alarm system. This translates to improved fault visibility and safer startup sequences in automated lines. The two sensor circuits monitor PTC sensors with configurable single or accumulative evaluation and offer short-circuit detection that can be auto, manual, or remote reset, delivering precise protection aligned to machine duty cycles. In practice, this reduces nuisance trips and supports proactive maintenance planning, especially in high-cycle applications like fans and pumps. Non-volatile fault storage, configurable, preserves fault history even after power removal, which accelerates root-cause analysis during scheduled maintenance and compliance audits. Screw connections with double-chamber cage terminals simplify wiring in tight panels, while 22.5 mm width and 85.6 mm height fit standard DIN rail enclosures. The ATEX approval and robust insulation (Uimp up to 4 kV) provide assurance for hazardous environments, enabling safe installation next to motors in mining, chemical, or processing facilities. The compact footprint, 0.145 kg weight, and IP50 housing support easy retrofits in crowded control cabinets without compromising performance or safety. Typical field outcomes include measurable downtime reductions, improved motor life, and better alignment with predictive maintenance programs.