As versatile as your application

A new generation of soft starters for numerous drive tasks

The right soft starter for every application

The 3RW5 family of soft starters is a comprehensive soft starter portfolio that has been developed for a wide range of applications and is simple to select, install, and configure. These starters are ready for the Internet of Things (IoT), being easily integrated into most industrial communication networks. Communications via Profinet, Modbus and Ethernet IP, along with HMI panels, are available across the entire product range. Whether your motor application is for pumping, fans, or crushing, the 3RW5 soft starters can handle each and every load; giving you peace of mind.

Select the right soft starter

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High Performance Sanftstarter

High performance

SIRIUS 3RW55 high performance soft starter

The SIRIUS 3RW55 soft starter offers comprehensive functionality. It efficiently performs complex starting and stopping tasks. The integrated smart functions (such as pump cleaning, pump stopping, automatic parameterization and condition monitoring) support users in the smooth operation of their plant.


  • Three phases controlled for application flexibility
  • Compact size - Less than 8" deep up to 400HP, easy to fit into MCCs, shallow cabinets and retrofits
  • Five available communication protocols: PB, PN-std, PN-HF, MB-TCP, EIP (future), MB-RTU (future)
  • HMI with color display, local interface and a slot for microSD memory card
  •  Wide range of control voltages: 24 V AC/DC and 110 - 250 V AC
General Performance Sanftstarter

General performance

SIRIUS 3RW52 general performance soft starters

The SIRIUS 3RW52 soft starter is the ideal alternative for star-delta starting applications. It is applicable for any type of motor.


  • Three phases controlled for application flexibility
  • Selectable analog or thermistor input for optimal protection of motor and load
  • Flexible HMI choices – Install the high feature, standard, or omit the display based on the application requirements.
  • Five available communication protocols: PB, PN, MB-TCP, EIP (future), MB-RTU (future)
  • Operator panel with optional display
  • Wide range of control voltages: 24 V AC/DC and 110 - 250 V AC
Basic Performance Sanftstarter

Basic performance

SIRIUS 3RW30/3RW40 basic performance soft starters

The SIRIUS 3RW30/40 soft starter is the ideal alternative starter 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

Which soft starter technology should I invest in?

The new Sirius 3RW5 soft starters can be used in a host of applications thanks to specific functions-from pumping, ventilating and compressing, to moving and processing. In addition, they feature special functions such as starting time monitoring, automatic parameterization depending on motor startup, pump stop to avoid pressure peaks in piping systems, and condition monitoring with warning and alarm limits.
SIRIUS 3RW5 soft starter at a glance

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A portfolio for all requirements

From two-phase soft starters for standard applications to high-performance three-phase soft starters, covering motor ratings of 1.5 to 1,600 hp, the 3RW5 soft starters have it all!

Smart functionalities at a glance

Thanks to comprehensive and specific functions, our powerful, coordinated portfolio of soft starters is suitable for a wide range of applications.


No matter which industry you work in, take advantage of intelligent functions such as condition monitoring, automatic parameterization, pump cleaning, and integrated brake functions.

Your application in mind

The best of both worlds with hybrid switching technology

Hybrid switching technology combines the advantages of electronic control with power semiconductors and the low conducting losses of switching contacts. The strengths of each technology are exploited during the appropriate operating phase.


As the motor starts, the soft starter is operated via the power semiconductors, which enable precise and targeted control of the starting current. After the motor has been softly started using semiconductors, the low-loss switching contacts take over the current until the motor is switched off.


The hybrid switching technology ensures a longer service life for switchgear due to the reduced wear when switching on.

Differences between the switching technologies

Benefit along the entire value chain

The digital transformation of industry is in full swing and our latest generation of soft starters supports companies in fully embracing the potential of digitization. The Simulation Tool for Soft Starters (STS) helps users to easily select devices for their application.


The SIRIUS Soft Starter ES software in the Totally Integrated Automation Portal (TIA Portal) enables you to quickly and easily perform parameterization (3RW55) and monitoring as well as diagnostics in the event of servicing SIRIUS general and high performance soft starters. The device parameters can be set directly on a PC and transferred to the soft starter via Ethernet cable or a PROFIBUS/PROFINET connection.


Connecting our soft starters to MindSphere, our cloud-based, open IoT operating system, gives you further options; cross-plant diagnostics, convenient process optimization, plant-wide access to control data, as well as process and measured values, predictive maintenance, energy data management, and resource optimization.

Simulation Tool for Soft Starters (STS)

With the Simulation Tool for Soft Starters (STS), we provide a convenient way to design soft starters using a simple, quick, and user-friendly interface. You just need to enter the motor and load data to simulate the application. The tool then suggests suitable soft starters.


  • Detailed, up-to-date Siemens motor database, including IE3 motors
  • Fast simulations with a minimum of input data
  • Immediate, graphical curve charts of start operations with limit values
  • Table view of soft starters suitable for the application

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SIRIUS Soft Starter ES engineering tool based on the TIA Portal

SIRIUS Soft Starter ES is the central software for project planning, commissioning, operation, and diagnosis of the SIRIUS 3RW5 general and high performance soft starter series.

SIRIUS Soft Starter ES is seamlessly integrated into the central Totally Integrated Automation Portal (TIA Portal) Engineering Framework, thus providing users with a consistent, efficient, and intuitive solutions for all their automation tasks.


  • Parameterization and diagnosis directly on the device via PROFINET.
  • Display of all operational, service, and diagnostics data
  • Important information for preventing failures or for quickly locating and correcting errors.

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More Information

Here you’ll find documents and videos on our offerings as well as additional information.