Soft Starters

A device used with AC electric motors to temporarily reduce the load and torque in the powertrain during start-up, protecting the motor and extending its lifespan.

Siemens | SIRIUS 3RW Soft Starters

The Siemens SIRIUS 3RW family is a comprehensive range of motor controllers designed to cover everything from simple conveyor belts to high-inertia industrial fans. They are favored for their “Hybrid Switching Technology,” which reduces wear on the internal contacts and increases the device’s service life.

SIRIUS 3RW30

Model Number: 3RW3017-1BB14 (12.5A / 24V AC/DC)

Two-phase control; compact size (up to 55 kW); optimized for simple, low-torque startups.

Key Technical Specifications:

  • One of the smallest footprints in the industry, allowing for side-by-side mounting without clearance gaps up to 60°C.

  • Uses semiconductors for the start/stop phase and mechanical contacts for the run phase to minimize heat and electrical wear.

  • Commissioning is handled via simple potentiometers—no complex software or programming required for basic operation.

SIRIUS 3RW55

Model Number: 3RW5217-1AC14 (18A / 110-250V AC)

Three-phase control; integrated HMI with display; supports PROFINET/EtherNet/IP; up to 1200 kW.

Key Technical Specifications:

  • Intelligent “Auto-Parameterization” feature adapts the starter to the motor’s load behavior automatically during startup.

  • Features a “Pump Cleaning” mode that briefly reverses the motor to clear debris from impellers.

  • Certified for safety applications (SIL 3 / PL e), allowing for safe motor stopping without additional safety relays.

Allen-Bradley | SMC™ Smart Motor Controllers

Allen-Bradley’s SMC range provides some of the most advanced diagnostics in the motor control world. They are highly scalable, with the “Flex” and “SMC-50” series offering modular designs that allow users to add communication and specialized protection modules as needed.

SMC™-3

Model Number: 150-C19NBD (19A / 480V)

Three-phase control in a compact frame; integrated bypass; 5 start/stop modes; up to 480 A.

Key Technical Specifications:

  • Automatically closes mechanical contacts once the motor is at speed, reducing heat generation and energy consumption.

  • Ensures balanced electrical stress on the motor windings compared to cheaper two-phase alternatives.

  • Built-in motor protection with adjustable trip classes (10, 15, or 20), eliminating the need for an external overload relay.

SMC™ Flex

Model Number: 150-F135NBD (135A / 480V)

Removable control and power modules; integrated LCD; 9 start/stop modes including “Smart Motor Braking.”

Key Technical Specifications:

  • Provides rapid motor stopping for applications like saws or grinders without requiring external braking resistors.

  • Specifically designed to eliminate “Water Hammer” by providing a unique, non-linear ramp-down curve for fluid systems.

  • Allows the motor to run at a fraction of its base speed (forward or reverse) for precise positioning or maintenance tasks.

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