What this soft starter delivers
The Siemens 3RW5074-2TB04 is a SIRIUS 3RW5 soft starter rated for a minimum setting current of 135 A across a supply voltage range of 200 to 480 V. It is configured for Trip Class 10A, 10E (preset), or 20E per IEC 60947-4-2, which governs how quickly it disconnects under overload — 10A is the tightest for fast-starting loads like conveyors, while 20E gives more headroom for high-inertia starts like fans or centrifuges. This unit carries ATEX, UKEX, and IECEx approvals, meaning it is certified for use in potentially explosive atmospheres — a requirement for chemical, oil-and-gas, or grain-handling installations where a standard soft starter would not be permitted. Fieldbus integration is comprehensive: PROFIBUS, PROFINET standard, Modbus RTU, Modbus TCP, and EtherNet/IP are all supported, so it drops into most automation architectures without a gateway. PROFIenergy is available when used with a PROFINET communication module, allowing energy management during idle phases.
The 3RW5074-2TB04 measures 160 mm wide, 230 mm high, and 282 mm deep, and mounts via screw fixing on a vertical surface. The mounting surface can be rotated ±90° or tilted ±22.5° forward/backward, giving panel builders flexibility in tight enclosures. Clearance requirements: 100 mm upward, 75 mm downward, 10 mm forward, 5 mm sideways, and zero backward — plan the gland plate and ventilation accordingly. Shock resistance is 15 g / 11 ms, with potential contact lifting above 12 g / 11 ms, so it holds up on vibrating machinery like compressors or crushers.