Siemens 3RU2126-4CC0 Three-Phase Thermal Overload Relay

Siemens 3RU2126-4CC0 is a Sirius 3RU2 three-phase thermal overload relay designed to protect motors from overload and phase faults in line with standard Siemens motor starters. It provides a controllable current range of 17–22 A, delivering class-10 protection for reliable, inverse-time trip behavior and preventing overheating under abnormal running conditions. This frame-size S0 device is intended to mount on the main circuit of a contactor, with spring-terminal connections for both the main circuit and the auxiliary circuit, and it supports a manual-automatic reset to suit differing maintenance regimes. The unit includes one normally open (NO) and one normally closed (NC) auxiliary contact, enabling integration with control logic for fault signaling or interlocking. The 3RU2126-4CC0 is listed as an 11 kW motor protection option within the 3RU2 family, aligning its current rating with typical medium- to large-capacity three-phase motors. This overload relay is part of Siemens’ Sirius protection suite and is commonly paired with compatible Siemens contactors to ensure coordinated protection in industrial drives and motor starters.