SIMATIC reversing motor starter for distributed control
The Siemens SIMATIC 3RK1304-5LS40-5AA3 is a reversing motor starter, meaning it can start a motor in either direction — forward or reverse — without an external contactor pair. It mounts via screw fixing in either vertical or horizontal orientation, giving flexibility for cabinet layout. Communication is handled through PROFINET and PROFIBUS DP protocols, so it integrates directly into Siemens automation architectures without a separate gateway. The supply voltage is 24 V DC nominal (20.4 to 28.8 V range), which powers the control electronics and the integrated bypass circuit that dissipates 3.888 W when active.
The breaking capacity at 400 V is listed at 100,000 A. For a panel builder, that simplifies coordination and saves a fuse holder. The unit has 2 bytes of digital inputs and 2 bytes of digital outputs. The number of physical digital inputs is 0 and the connector for digital input signals is an M12 socket. The vibration resistance is 2g and shock resistance is 15g for 11 ms. These are typical for industrial cabinet-mounted gear — no special derating needed for most factory-floor environments, but the shock spec means it can handle occasional impacts during conveyor or press operations.