Siemens 3RU2126-1KB0 Three-Phase Thermal Overload Relay

The Siemens 3RU2126-1KB0 is a three-pole thermal overload relay from the Sirius 3RU2 family, designed for direct mounting on size S0 motor contactors to protect three-phase motors. It provides thermal overload protection with a trip current range of 9.0 to 12.5 A, Class 10 accuracy, and features a manual-automatic-reset option with screw-type main and auxiliary circuit terminals. Designed for use with Siemens 3RT contactors, the relay supports insulation up to 690 V and withstands surge voltages up to 6 kV, with a typical power loss around 5.1 W. Its compact, direct-mount form enables integrated motor protection in tight control panels without additional mounting hardware.