Thermistor motor protection relay Standard evaluation device 17.5 mm housing Spring-loaded terminal 1 make contact, 1 break contact US = AC/DC 24 V-240 V Auto-RESET suitable for bimetal switches 2 LEDs (READY/TRIPPED) galvanic isolation Thermistor motor protection relay SIRIUS 3RN2 for protecting motors from overheating by direct temperature measurement. The direct measurement of the motor winding temperature enables the protection of a motor even under unusual conditions such as heavy starting, braking, frequent switching or inadequate cooling and thus saves the need for precautionary oversizing of the motor. By using PTC sensors or bimetal switches, parameterization of the devices is not necessary. LEDs enable rapid error diagnosis. The devices are climate-proof, touch-safe and can be used worldwide thanks to the 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 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 top hat rail or for screw fastening with adapter (accessory) and with hard gold-plated contacts. Uniform accessories for all device variants, such as removable terminals, push-in lugs and coding pins simplify selection and storage. The 3RN2 thermistor motor protection relays replace the proven 3RN1 series. SIRIUS Relay - a program for all cases.
| Property | Value |
| Number of contacts as normally closed: | 1 |
| Number of contacts as normally open: | 1 |
| Number of measuring circuits: | 1 |
| Width: | 17.5 mm |
| External reset possible: | no |
| Error storage possible: | no |
| Height: | 100 mm |
| Depth: | 90 mm |
