Thermistor Motor Protection Relay Standard Evaluation Device 22.5 mm Housing Screw Connection 2 Changeover Contacts US = AC/DC 24 V-240 V Manual/Auto/Remote RESET with ATEX Approval. 2 LEDs (READY/TRIPPED) ensure safe galvanic isolation, Test/RESET button, wire break monitoring, 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, thus avoiding the need for precautionary oversizing of the motor.

The devices can be used to protect motors in gas or dust explosion hazardous areas. The use of PTC sensors eliminates the need for parameterization of the devices. LEDs enable quick fault diagnosis. The devices are climate-resistant, touch-safe, and can be used worldwide thanks to a wide voltage range and international approvals.

Available as mono- or bistable evaluation devices, with and without ATEX approval, with one or two sensor circuits, and with auto, manual, and/or remote RESET. The devices are available in screw or spring clamp technology (Push-In). There are versions with a width of 17.5 mm or 22.5 mm, for TH35 rail mounting or for screw fastening with an adapter, as well as with hard gold-plated contacts. Uniform accessories for all device variants, such as detachable 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.