Temperature Monitoring with NO Special Software Required

Temperature Monitoring - Know It, Control It!

SIRIUS 3RS25 temperature monitoring relays can be used to measure temperatures in solid, liquid, and gas media. The temperature is recorded by a sensor in the medium, evaluated by the device, and monitored to determine whether it is within the upper and lower temperature limits.


  • Motor and system protection
  • Control cabinet temperature monitoring
  • Frost monitoring
  • Temperature limits for process variables e.g. in the packaging industry or electroplating
  • Controlling equipment and machines such as heating, air-conditioning and ventilation systems, solar collectors, heat pumps or warm water supplies
  • Motor, bearing and gear oil monitoring
  • Coolant monitoring
  • Overload protection in transformer windings
  • Simple two-point temperature controllers

MORE Functions in LESS Space!

Siemens Sirius 3RS2 Relay Features:
  • Available in an analog or digital version.
  • The devices being monitored can be reset manually, by remote access, and/or automatically.
  • Built-in memory function ensures that the last device state is stored and recovered in the event of a blackout.
  • The digital devices are also available with an IO link, so that temperature data can be forwarded to higher-level controllers and integrated in open cloud-based IoT systems, such as MindSphere.
  • Relays are certified according to functional safety standards and can be used in safety applications up to SIL 1 / PL c.
  • Can be used in industrial furnaces and burner applications.


  • Versions for a sensor, a threshold value, and for Pt100 sensor types as well as thermo elements J and K for the most common temperature ranges
  • Permanent wiring due to removable terminals in screw and spring-type technology (push-in)
  • Compact, easy to adjust two-point controller (overshoot and undershoot)
  • Relay changeover outputs for direct switching of loads and simultaneous use of the NC contact as the signaling contact
  • Easy operation using rotary potentiometer and settable hysteresis (5%, 10%, 15%, 20%)
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