Thermistor motor protection relay standard evaluation device with a housing of 22.5 mm. It features spring-loaded terminals, 2 changeover contacts, and a supply voltage of AC/DC 24 V-240 V. The device offers manual, automatic, and remote reset with ATEX approval, as well as 2 LEDs (READY/TRIPPED) for safe galvanic isolation. It is equipped with a test/reset button, wire break monitoring, and short circuit monitoring, and is safe against zero voltage.

The SIRIUS 3RN2 thermistor motor protection relay protects motors from overheating, even in explosive environments, through direct temperature measurement with ATEX approval. The direct measurement of the motor winding temperature allows for the protection of a motor under unusual conditions such as heavy starting, braking operation, frequent switching, or insufficient cooling, thereby avoiding unnecessary oversizing of the motor.

The devices can be used in gas or dust explosive areas. Thanks to the use of PTC sensors, parameterization of the devices is not necessary. LEDs enable quick fault diagnosis. The devices are climate-resistant, touch-safe, and can be used worldwide due to their wide voltage range and international approvals.

Available are mono- or bistable evaluation devices, with or without ATEX approval, with one or two sensor circuits, as well as with automatic, manual, and/or remote reset. The devices are available in screw or spring-loaded technology (Push-In). There are versions with a width of 17.5 mm or 22.5 mm, for TH35 mounting rails or for screw fastening with an adapter, as well as with hard gold-plated contacts. Uniform accessories for all device variants, such as removable terminals, insertion tabs, and coding pins, simplify selection and inventory management.

The thermistor motor protection relays 3RN2 replace the proven series 3RN1. SIRIUS relays - a program for all cases.