Siemens 3RW3037-1BB04 Soft Starter

The Siemens 3RW3037-1BB04 SIRIUS soft starter, Size S2, provides controlled, reduced-voltage starting for three-phase motors to limit inrush current and mechanical shock during acceleration, helping protect drive trains and electrical infrastructure in automation systems. It is rated for 63 A and 30 kW at 400 V, supports a 200–480 V AC supply range, and uses a 24 V control supply (24 V AC/DC) with screw terminals for reliable, straightforward wiring. Designed for ambient temperatures up to 40 °C, the unit also features an integrated bridging contact system to simplify wiring and improve fault tolerance in standard automation installations. Typical applications include starting and soft-start control of fans, pumps, conveyors and other medium-power motors in industrial environments, where gradual ramping of motor voltage supports smoother operation and extended motor life. As a member of the SIRIUS soft starter family, 3RW3037-1BB04 combines Siemens engineering with compact packaging designed for panel installations in standard automation cabinets.