SIRIUS 3RF34 Solid-State Contactors The solid-state contactors for the wear-free and noiseless switching of motors are designed for the frequent switching on and switching off of AC drives up to 5 HP as well as reversing up to 3 HP. These devices are fully insulated and can be mounted directly on motor protectors and overload relays or SIRIUS current monitoring relays, which makes them really easy to integrate into motor feeders. These 3-phase solid-state contactors are equipped with a 2-phase control which is particularly suitable for typical motor circuits without a connection to the neutral conductor.