Safety is a SIRIUS business - 3SK safety relays

SIRIUS 3SK safety relays

SIRIUS 3SK safety relays offer outstanding simplicity, flexibility and cost-effectiveness. Their modular design simplifies the planning, commissioning and expansion of plants. Simple safety functions, such as EMERGENCY STOP and protective door monitoring up to SIL 3 and PL e, can be quickly implemented without programming. The safety relays are certified in accordance with IEC 62061 and ISO 13849-1 and are internationally applicable. The 3SK1 and 3SK2 versions of the device are available to meet differing requirements. The devices can be used for both stand-alone and integrated solutions.

Technical specifications for 3SK safety relays

Industry Mall

Always a task for SIRIUS 3SK safety relays

There are many facets to machine safety

Regardless of whether the application involves the fail-safe monitoring of a mechanical or an electronic sensor, there are no major differences between the safety relays that can be used. Therefore, with SIRIUS 3SK you are choosing an extremely lean portfolio. Standard safety applications can be implemented quickly and easily even with 3SK1 safety relays. 3SK2 devices that can be parameterized by software are available for applications with more complex safety requirements. They can be connected to higher-level control systems via PROFINET.


Basic units

3SK1 standard and advanced basic units

With SIRIUS 3SK1 safety relays, safety functions can be simply parameterized with DIP switches. Operation of a sensor is always followed by fail-safe disabling of all outputs of these basic units.


  • Seamless integration: reduces wiring effort for fail-safe SIRIUS 3RM1 motor starters
  • More free space: fewer basic units and main circuit components
  • Extremely compact: narrow overall width and multifunctionality


The standard basic units are characterized by easy handling and they are available with relay and solid-state outputs.



In addition to the product features of the Standard basic units, the advanced basic units also offer:

  • A modular system structure: additional sensors can be connected via flexibly combinable input expansionsßen
  • Reduced wiring: the simple plug-in device connector eliminates wiring errors
  • Time delay: easily adjustable with the rotary coding switch


Basic units

3SK2 basic units

While the 3SK1 safety relays always ensure simultaneous fail-safe disabling of all outputs, the fail-safe outputs on the 3SK2 devices can be disabled individually.


  • Maximum functionality with the smallest of footprints
  • Slimline unit with a large number of inputs and outputs
  • Selective tripping by independent outputs
  • High degree of flexibility: parameters can be assigned with simple software
  • Greater cost-effectiveness and modularity: 3SK1 output expansions can be added using device connectors (less wiring effort)
  • Individually selectable time functions
  • Integrated unit: fail-safe SIRIUS 3RM1 motor starters are seamlessly integrated using device connectors
  • Connection to PROFINET and PROFIBUS for simple parameter assignment, connection to the control level, and for diagnostic purposes

Expansion units

Input/output expansion

Input/output expansion for 3SK safety relays

Input and output expansions are available for the expansion units for 3SK safety relays:


With the 3SK1220 sensor expansion and 3SK1230 power supply input expansions, the 3SK1 advanced basic units can be made more flexible.


The 3SK1211 output expansion expands the safe outputs of a 3SK1 or 3SK2 basic unit by adding four safe floating outputs, and the 3SK1213 output expansion by adding three safe outputs with high switching capacity.

3SK2 software and simulator


High-tech safety functions for parameter assignment and simple simulations that do not require programming knowledge

Simple parameter assignment: safety functions without requiring programming knowledge


The SIRIUS Safety ES engineering software offers extensive support to users for engineering, commissioning and documentation by means of consistency checks, online diagnostics, forcing and engineering documentation.


  • With SIRIUS Safety ES, parameters are easily assigned by drag & drop with ready-made, certified blocks. These also include complex, sophisticated safety functions, such as protective doors with locking and muting.
  • SIRIUS Safety ES also offers extensive support for commissioning and diagnostics. This reduces both the commissioning effort and the costs of plant downtimes.
  • Once created, a parameter assignment can be replicated any number of times and transferred to other 3SK2 units.


Simply clever: simulating applications offline


With the free 3SK2 simulator, you can get to know the full range of functions of the 3SK2 with ready made applications and create and test configurations in advance. This lets you find the appropriate device for the application without any diversions. This saves substantial time and money on engineering, because no real components are required and applications can be quickly and easily adapted.


3SK2 communication


Communication via PROFINET/PROFIBUS

With the optional interface modules for PROFINET and PROFIBUS, the 3SK2 safety relays can be integrated on the control level for exchanging process data or diagnostics purposes. Furthermore, it is also possible to connect to the Safety ES via the respective communication network with the switching devices.


The 3SK2511 interface module is available for connection to PROFINET and the 3RK3511 for connection to PROFIBUS.

Application examples for safety relays

Application manual