Siemens 3RU2136-4FD0 Overload Relay

Siemens 3RU2136-4FD0 is a SIRIUS thermal overload relay designed to protect three‑phase motors in motor starter circuits by monitoring current and overheating. Part of the 3RU2 family, it is intended for use with Siemens contactors to form compact motor protection assemblies. The 4FD0 variant specifies a current range of 28–40 A and provides a single normally open and one normally closed auxiliary contact (1 NO/1 NC) for signaling or interlocking. It supports a maximum operating voltage up to 690 V and a full-load current rating of 40 A, making it suitable for motor protection up to that level. The main circuit connections are screw terminals, with the auxiliary connections configured per the installation. Typical applications include safeguarding industrial motors such as conveyors, pumps, and fans, as well as other three‑phase loads where reliable thermal overload protection and straightforward electrical signaling are required. This relay is designed to integrate within Siemens’ Sirius ecosystem alongside compatible 3RU2 accessories and contactors to deliver integrated motor protection in industrial control panels.