As versatile as your application

SIRIUS 3RW5 family of soft starters

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The right soft starter for every application.

The SIRIUS 3RW5 soft starters are the best alternative when direct or star-delta starting doesn’t apply to three-phase motors, because you often have to be concerned with mechanical impact in the machine or voltage drops in the line supply.

This new family was also built with your motor application in mind; 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.

Selecting and dimensioning the right soft starter.

Below you can choose between three levels of sophistication; basic, general and high performance, covering motor ratings of 1.5 to 1,600 HP.


High Performance


General Performance


Basic Performance

SIRIUS 3RW44 for high-feature applications

Thanks to its outstanding functions, the SIRIUS 3RW44 handles difficult start-up and deceleration processes in a simple and, above all, gentle manner. With its innovative torque control system, it can be used for drives with a power output up to 710 kW at 400 V – respectively 950 hp at 460 V – in an inline circuit or up to 1200 kW at 400 V – respectively 1700 hp at 460 V – in an inside-delta circuit. Designed for simple handling, the functions are exceptionally easy to use.

- Optimum acceleration due to torque control
- Simple and fast commissioning thanks to user-friendly display
- Savings in size and costs due to optional inside-delta circuit
- Simple integration in higher-level control units via PROFIBUS


COMING SOON: 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.

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


SIRIUS 3RW52 general performance soft starter

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

- 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 motors in performance classes from 5.5 to 560 kW


SIRIUS 3RW30/3RW40 basic performance soft starter

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


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  • Automatic Parameterization

    Automatic parameterization simplifies the commissioning and operation of critical applications, even in the case of highly dynamic load characteristics.

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  • MCC and Drive

    Electrical Robustness

    Due to the wide control voltage range from 110-250 V AC, soft starters have a high degree of electrical robustness. This guarantees reliable operation even in the event of voltage drops.

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  • Pump Cleaning

    The pump cleaning function prevents pumps from getting blocked. This increases your productivity and system availability.

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Application Examples

Smart functionalities at a glance.

Our powerful portfolio of soft starters with SMART functions 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:

Condition monitoring

Example: Compressors

The evaluation of the electrical data and motor active power of our soft starters enables condition monitoring, which gives you a new type of transparency over the status of equipment. Based on the measured data, you can determine whether a pump is running dry, the oil or lubricating film on compressors is wearing off, or a ball bearing is showing signs of impending damage.

Automatic parameterization

Example: Conveyor belts

The soft startup of conveyor belts must constantly adjust to new conditions as the starting weight changes. The SIRIUS 3RW5 soft starters simplify this task with their auto-parameterization function. By analyzing the startup, the soft starter identifies the load conditions and sets the appropriate values for optimally starting the belt.

Integrated brake functions

Example: A Sawmill

The slow and heavy saw blades used in industrial sawing plants require a soft starting function to protect electrical and mechanical systems.
Saw blades must be able to brake quickly to save time when switching.
Thanks to its integrated brake function, the 3RW55 automatically supports DC braking and reverse braking, including the control of components such as braking contacts and reversing contactors.

Pump Cleaning

Example: Wastewater

Pumps are used to carry liquids in a variety of applications. In wastewater applications, dirt and particles in the wastewater can be deposited on the pump blade wheels and reduce pumping capacity and productivity. The pump cleaning function prevents this from happening; integrated measurement technology detects the dirt and changes the pump’s direction of rotation as soon as defined limit values are exceeded.

Pump Stopping

Example: Water Supply

When pumps are used to carry large volumes of water in the public water supply system; like for a building or a pump station, shutting them down is challenging. Based on their design, pumps stop immediately which results in “water hammer” in pipes, couplings, valves, and seals caused by the kinetic energy of the transported volume in the piping system.. To avoid damage, the 3RW52 and 3RW55 soft starters have a pump stopping mode. The mode allows the pumps to stop in a controlled manner.

Electrical Robustness

Example: Fans

Fans for air conditioning systems, buildings, tunnels or car-parks are substantially big, taking up a lot of startup time. These factors result in temporary drops of the supply voltage. Soft starters themselves require a control supply voltage of 230 V and a primary voltage of 400 V. The SIRIUS 3RW30/40/5 soft starters have a wide-range of voltage versions, such as 110 to 250 V AC for the 3RW52/55. Even in the case of a voltage drop, the soft starter is fully operational. This means that the motor and the application are fully functional as well. Thanks to the electrical robustness of our soft starters, operation is also guaranteed in power supply networks with occasional power dips.

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