SIRIUS 3RR2 and 3UG4 Monitoring Relays for electrical and additional measurements

Maximum protection for machines and plants

Protect your machines and equipment in the best possible way – with the SIRIUS 3UG4 and 3RR2 monitoring relays.

Monitoring relay SIRIUS 3UG4

With the SIRIUS 3UG4 monitoring relay, power system and voltage faults can be identified and rectified at an early stage, before extensive damage occurs. The relays allow for the individual assignment of parameters as well as distinct diagnostics.

Our highlight:
The monitoring relays SIRIUS for IO-Link - for seamless industrial communication.

Advantages of the SIRIUS 3UG4:

Time and space savings:

  • Screw-type and spring-loaded terminal for fast and safe wiring

  • Display of actual value and fault type for fast trouble-shooting

  • Less space requirements in the control cabinet thanks to the 22.5 mm width


  • Parameters for reset behavior and operating principle can be set individually

  • Reduced variety of different types and wide measuring range for reduced stock-keeping

  • Wide range power supply for worldwide use

High availability:

  • Removable terminals for device replacements without system interruption

  • Reliable diagnostics thanks to shiftable error memory

Monitoring relay SIRIUS 3RR2

The SIRIUS 3RR2 monitoring relay, which is simply plugged on to a contactor, not only serves the monitoring of motors or other consumers, but rather protects your entire application. Especially during installation it offers an important advantage: By integrating the relay directly into the load feeder, wiring is reduced substantially.

Our highlights with the SIRIUS 3RR2:

  • Fast diagnostics thanks to clear error messages at the display

  • Optimally matched to the technical characteristics of the SIRIUS 3RT2 contactors, therefore no separate current transformer is required

  • Direct mounting to contactors reduces wiring efforts in the main circuit and potential wiring faults

SIRIUS 3UG and 3RR2 monitoring relays for IO-Link

For seamless industrial communication

The relays SIRIUS by Siemens offer maximum machine and system protection and now - thanks to IO-Link - also communicate with the control level. Enjoy greater flexibility with the monitoring relays SIRIUS for IO-Link: In addition to the unchanged autonomous monitoring function, measured values and data can directly be transmitted to the control via IO-Link. Also parameter assignment can either be done locally or via IO-Link. Benefit from considerably simplified device replacement – thanks to data synchronization and automatic parameter assignment via parameter server.

Available with IO-Link connection:

  • SIRIUS 3UG48 for IO-Link: for the monitoring of electrical and mechanical parameters

  • SIRIUS 3RR24 for IO-Link: for the monitoring of 3-phase currents - directly integrated in the motor feeder