SIRIUS 3RV1 Motor Starter Protectors Siemens SIRIUS 3RV1 Motor Starter Protectors are compact current-limiting devices optimized for load feeders. The Siemens SIRIUS 3RV1 Motor Starter Protectors are used for protecting and switching three-phase motors and other loads. The scalable setting ranges allow a suitable motor starter protector to protect all standard motors at ambient temperatures of ≤60°C. 3RV1.11 Motor Starter Protectors include a toggle switch.