Siemens 3RU2126-4DB0 is a three-pole thermal overload relay for motor protection in size S0, designed to mount with Siemens 3RT2-size S0 contactors. It is rated for 20–25 A (thermal) and Class 10 protection, with screw terminals for both the main circuit and the auxiliary circuit, and it supports manual or automatic reset. This overload relay forms a compact starter package when paired with compatible contactors, providing reliable protection for three‑phase motors in industrial controls.
