Siemens 3RU2126-4CB0 is a Sirius 3RU2 thermal overload relay designed to protect three‑phase motors, rated for 17–22 A in size S0 with Class 10 protection, and intended for mounting on Siemens contactors to provide integrated motor protection. It uses screw-terminal connections for both the main circuit and the auxiliary circuit and offers manual-automatic reset, with auxiliary contacts configured as 1NO + 1NC to signal status in control circuits. The device is suitable for stand-alone installation or as part of a contactor assembly and operates from -40 to 70 °C.
