3RW4458-6BC44 Soft starter SIRIUS 3RW44 970A 400V

Siemens SIRIUS 3RW44 Soft Starters — Professional High-Performance Three-Phase Control

The Siemens SIRIUS 3RW44 soft starter range is designed for highly demanding industrial environments, covering motor capacities from 15 kW to 710 kW (or up to 1200 kW when connected Inside-Delta). The series provides uncompromising symmetrical three-phase thyristor control throughout the starting and stopping cycles. High-precision Torque Control delivers linear acceleration without current spikes, and the integrated LCD screen simplifies programming and dynamic operation monitoring.

Typical Applications for Siemens 3RW44

• Mining Mills and Crushers: Delivers maximum breakaway starting torque utilizing high-torque Breakaway pulses to start fully loaded machinery.
• Large Wastewater and Drainage Pumps: Precise torque regulation during deceleration eliminates pipe vibration and check valve slam.
• High-Inertia Centrifugal Fans and Exhauster Impellers: Designed to sustain severe heavy-duty starting cycles (Heavy Duty) of up to 60 seconds duration.

What Differentiates Siemens 3RW44 from Competitors

Symmetrical three-phase control combined with Inside-Delta wiring compatibility allows installation designers to use smaller-sized conductors, reducing cabling costs.

When Siemens 3RW44 is NOT Suitable

• For simple lower-power drives where advanced torque regulation is not required — the economical Siemens 3RW30 series is preferred.
• If your B2B facility demands a soft starter that can run on two phases in an emergency if one thyristor fails — choose the ABB PSTX.

Our Commissioning Experience

The 3RW44 is a benchmark of reliability for B2B plants. Our installation division frequently utilizes the on-board DC braking function, allowing dynamic stopping of high-inertia heavy fans for fast maintenance access. Note that 3RW44 units rated above 250 A do not feature an integrated bypass; an external bypass contactor must be included in your panel layout.