Thermistor Motor Protection Relay Standard Evaluation Device with a 22.5 mm housing and screw connection. It features 2 changeover contacts, suitable for AC/DC 24 V, with auto-reset and is compatible with bimetal switches. Two LEDs (READY/TRIPPED) provide quick fault diagnosis. The SIRIUS 3RN2 Thermistor Motor Protection Relay protects motors from overheating through direct temperature measurement. This measurement of the motor winding temperature allows for protection even under unusual conditions such as heavy starting, braking operation, frequent switching, or insufficient cooling, thereby avoiding unnecessary oversizing of the motor. The use of PTC sensors or bimetal switches does not require any parameterization of the devices. The devices are climate-resistant, touch-safe, and can be used worldwide thanks to a wide voltage range and international approvals. They are available as mono- or bistable evaluation devices, with and without ATEX certification, with one or two sensor circuits, and with auto, manual, and/or remote reset options. The devices are available in screw or spring-loaded (Push-In) technology. There are versions with a width of 17.5 mm or 22.5 mm, for TH35 rail mounting or for screw mounting 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 3RN2 Thermistor Motor Protection Relays replace the proven 3RN1 series. SIRIUS Relays - a program for all cases.