Thermistor Motor Protection Relay Standard Evaluation Device with a 22.5 mm housing and screw connection. It features 2 changeover contacts and is suitable for AC/DC 24 V-240 V with auto-reset, compatible with bimetal switches. Equipped with 2 LEDs (READY/TRIPPED), it offers galvanic isolation. The SIRIUS 3RN2 thermistor motor protection relay protects motors from overheating through direct temperature measurement. This measurement of the motor winding temperature allows for motor protection even under unusual conditions such as heavy starting, braking operation, frequent switching, or insufficient cooling, thus preventing unnecessary over-dimensioning of the motor. The use of PTC sensors or bimetal switches does not require device parameterization. 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. They are available as mono- or bistable evaluation devices, with or without ATEX certification, 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 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, plug-in 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.