Siemens AG 3RU2126-1DB0 Thermal Overload Relay

Siemens SIRIUS 3RU2126-1DB0 thermal overload relay is a 3-pole device (size S0) designed to protect three-phase motors and mount directly on Siemens 3RT2 contactors. It provides an adjustable current setting from 2.2 to 3.2 A, supports Class 10 trip protection, and offers a manual-automatic reset with a trip indicator for fast fault diagnosis. The relay uses screw terminals for both the main and auxiliary circuits, and includes one normally open and one normally closed auxiliary contact, enabling straightforward control signaling and interlock. Insulation is rated at 690 V with a 6 kV surge withstand, it carries IP20 protection on the front, and it operates across -40°C to +80°C for reliable performance in typical industrial environments. Designed for direct mounting on 3RT2 size S0 contactors, this overload relay is a standard choice for protecting motors in Siemens automation architectures.