The ABB CM-MPS.21S is a compact, multifunctional motor protection switch designed to provide reliable thermal overload and short-circuit protection for three-phase motors up to 3 kW. As part of ABB’s CM-MPS series, the CM-MPS.21S integrates switching, isolation, and motor protection in a single DIN-rail mountable device, eliminating the need for separate contactors and thermal relays. This model CM-MPS.21S features adjustable current settings (0.1–1.6 A), manual ON/OFF control, clear trip indication, and compliance with IEC/EN 60947 standards, making it ideal for use in HVAC systems, pumps, compressors, and small industrial machinery. With its space-saving design and tool-free installation, the CM-MPS.21S simplifies panel wiring while enhancing operational safety and maintenance efficiency.