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Entry type: Product note Entry ID: 109743523, Entry date: 12/05/2016

Delivery release for 3RN2 thermistor motor protection relay

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The delivery release for the new 3RN2 thermistor motor protection relays has been issued just in time for SPS 2016. The 3RN2 range is the successor to the successful 3RN1 series.

SIRIUS 3RN2 thermistor motor protection relays directly monitor the motor winding temperature and thus provide reliable plant protection. SIRIUS 3RN2 thermistor motor protection relays are well placed, even in potentially hazardous areas, thanks to ATEX approval: this ensures production is safely monitored even under the most difficult of conditions.

The advantages at a glance:

  • Optimum use of the available installation space in a control cabinet thanks to a width of only 17.5 mm (depending on the version)
  • Standardized enclosure concept for all devices in the new standard mounting rail enclosure
    • e.g. uniform accessories
    • Removable screw-type or spring-type terminals (push-in technology)
  • Suitable for bimetal sensors or type A thermistor sensors
  • ATEX versions developed according to DIN EN 50495 for SIL 1
  • Continuous self-diagnostics and monitoring of sensor circuits
  • All versions with supply voltage of 24 V AC/DC or 24 – 240 V AC/DC
    • For worldwide use
    • Simplified ordering and inventory management thanks to fewer device variants

Customer benefits:

Space-saving and easy to use/configure

  • New, titanium gray housing with many advantages, e.g. detachable terminals and narrow width
  • Wide-range supply voltage reduces number of device variants
  • Maintenance-free spring-type terminals or alternatively screw-type terminals
  • and much more!


  • Temperature measurement at thermally sensitive locations directly within the motor protects it from overheating

Optimal protection at all times

  • Can be used in potentially hazardous areas thanks to ATEX and SIL 1/PL c according to DIN EN 50495


  • Suitable for bimetallic sensors as an inexpensive alternative to high-cost sensors

Predecessor types:

3RN1 thermistor motor protection relays


The 3RN2 thermistor motor protection relays are intended to quickly replace the current 3RN1 series. Unrestricted availability of the predecessor series is only planned until September 30, 2019. Beyond this date, only the legally required supply of spare parts will be ensured.


The 3RN2 thermistor motor protection relays are functionally compatible with their 3RN1 predecessors.
Their width is either the same as or smaller than their predecessors.
As a result of logical separation between the input side (supply voltage, reset and sensor connection) and output side (relay contacts), however, the devices have a different terminal arrangement.

The current 3RN1062 thermistor motor protection relay version for 6 motors will no longer be available in the 3RN2 series. If necessary, this function can be achieved by scaling several individual units in accordance with requirements.

Ordering data

3RN2 thermistor motor protection relays

Additional information


  3RN2 thermistor motor protection relays flyer (281,3 KB)

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