Sanftstarter SIRIUS 3RW55 Failsafe

Fail-safe shutdown of soft starters

Stopping machines in safety-oriented applications quickly and reliably.

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 supplies any torque-generated energy in the event of an emergency. This saves you wiring time and space in the control cabinet.


With the standard SIRIUS 3RW soft starters, safe shutdown can be implemented by using additional accessories, for example, a 3SK1 safety relay and power contactors.




SIRIUS soft starters

Soft starters from the SIRIUS portfolio  are the best solution for soft starting and stopping of motors.

SIRIUS 3RW55 products in SiePortal

The integrated platform for product selection, buying and support.

Which safety level can I achieve with SIRIUS 3RW soft starters?

The SIRIUS 3RW55 Failsafe soft starters permit even difficult starting and stopping and ensure reliable, safety-oriented, shutdown without the need for any additional accessories. Integrated HMI and optional communication modules (Profinet/Profibus, Modbus, EtherNet/IP) enable flexible implementation of the high-performance soft starters.

For some applications, the SIRIUS 3RW55 Failsafe soft starter may not be the first choice: either because a standard soft starter is sufficient or because more functions are available with a 3RW55 high-performance soft starter without integrated safe shutdown (e.g. integrated braking, creep speed, bypass).


But even without the SIRIUS 3RW55 Failsafe soft starter, you don't have to do without a soft start in safety areas. All SIRIUS 3RW soft starters can be safely switched off using additional accessories. Depending on the setup, the SIL1/PLc, SIL2/PCd and SIL3/PLe safety levels can be achieved.

Related Content