Sirius 3RW5 Softstarters

The right soft starter for every application

The new harmonized SIRIUS 3RW5 soft starter generation offers the right hardware for all requirements. The SIRIUS 3RW5 soft starters can be optionally expanded with a communication module (PROFINET, PROFIBUS, Ethernet IP or Modbus RTU and TCP) and feature various HMI module options across the range.

Tested combinations for the entire motor feeder extend the range of possible uses. The compactly designed enclosure, which won the if-design award 2018, and the coated printed circuit boards contribute to a space-saving and rugged control panel assembly.

The new SIRIUS 3RW5 soft starter generation is fitted with modern hybrid switching technology to ensure efficient switching and energy-saving operation. This enables low-wear switching, extends the service life of the devices and provides mechanical protection for the drive train. The soft starting ensures that the devices avoid current peaks in the power supply system. All in all, using the new SIRIUS 3RW5 devices enhances the reliability of the application and increases the cost efficiency of the system.

3RW5 – Highlight Features

Fully tested type 1 and type 2 coordinated solutions

Suitable for every drive, can be simply integrated into the automation system

Versatile for every application including pumping, ventilating and compressing as well as moving and processing

System Integrator Program - Tools

Modern hybrid switching technology for efficient switching and built-in bypass for every size, saving energy and ensuring a long service life

3RW5 Range


Thanks to its maximum functionality, the intelligent SIRIUS 3RW55 soft starter masters difficult startup and stopping processes in a soft manner. Integrated smart functions (such as pump cleaning, pump stop, automatic parameterization, and condition monitoring) support users in the smooth operation of their plant.

  • 3-phase control for optimal motor start
  • Engineering in TIA Portal
  • Various bus connections (PROFINET, PROFIBUS, Modbus)
  • Integrated operator panel with display
  • Electrical robustness
  • For drives in performance classes from 5.5 to 1,200 kW

The SIRIUS 3RW52 soft starter is the ideal alternative to star-delta starters. As an all-rounder, it is applicable for any type of drive.

  • 3-phase control for optimal motor start
  • Parameterization over rotary setting elements
  • Various bus connections (PROFINET, PROFIBUS, Modbus)
  • Operator panel with optional display
  • Electrical robustness
  • For drives in performance classes from 5.5 to 560 kW

Thanks to their compact design, SIRIUS 3RW50 soft starters are the ideal starter solution for standard applications.

  • 2-phase control for standard applications
  • Parameterization over rotary setting elements
  • Integrated motor overload protection and intrinsic device protection
  • Electrical robustness
  • For drives in performance classes from 1.5 to 250 kW

Learn how to use the software with the free downloadable simulation tools

A further advantage when using the new 3RW5 generation of soft starters is the provision of data, for CAx tools like Eplan, for example. In addition, the Simulation Tool for Soft Starters (STS) helps the user to make a simple product selection as well as SIRIUS Sim software for testing the application. The new 3RW5 soft starters can be configured and commissioned easily and in a standardized manner in the TIA Portal using the Soft Starter ES engineering software. They are simply linked up to the automation system by means of the various communication options.

Simulation Tool for Soft Starter (STS)
SIRIUS Sim Software
SIRIUS Soft Starter ES V17 (TIA Portal)

Safe Torque Off (STO) is integrated for the first time in the SIRIUS 3RW55 Failsafe high-performance soft starters

When motors start or stop abruptly, mechanical impacts in the machine or voltage dips in the power supply may cause serious problems. These must also be avoided in safety areas.

The integrated Safe Torque Off (STO) function in the new SIRIUS 3RW55 Failsafe soft starter effectively ensures that the drive can no longer supply any torque-generated energy in the event of an emergency. The motor comes to a standstill and remains safely in this state until it is restarted (restart interlock). In this way STO facilitates risk-free working, even when the protective door is open, making it popular in processing machine applications and systems such as agitators or belt conveyors. This saves you wiring time and space in the control cabinet.

Download Full SIRIUS 3RW5 Essential Brochure
Find out more on the Siemens website