Siemens 3RU2136-4FB0 Overload Relay

Siemens 3RU2136-4FB0 is a SIRIUS thermal overload relay used for motor protection in three‑phase circuits, with a current range of 28 to 40 A. It is designed for direct mounting on Siemens 3RT contactors of size S2, providing Class 10 thermal protection and guarding motors against overload, phase asymmetry, and phase failure. The device features screw terminals for both the main circuit and the auxiliary circuit, and supports both manual and automatic reset operation to fit different start/stop schemes. It supports insulation voltage up to 690 V and operates in ambient temperatures from -40 °C to +70 °C, with a typical total power loss around 11 W. This overload relay is part of the 3RU2 family and is specifically identified as 3RU2136-4FB0, making it suitable for panel builders seeking a compact, directly mountable protection device for motors up to 40 A and up to 690 V.