SIRIUS 3RT10 Non-Reversing Contactors for Switching Motors The 3RT1 contactors are climate-proof. They are finger-safe according to EN 50274. The basic units of sizes S2 and S3 contain only the main current paths. All basic units can be extended with auxiliary switch blocks. For safety applications, complete units with permanently mounted 2NO + 2 NC switch blocks are available (connection designation according to EN 50012) are offered in all frame sizes. These versions are built according to special Swiss regulations “SUVA” and are distinguished externally by a red labeling tape.