Siemens 3SB3500-4BD01 Key-Operated Switch

Siemens 3SB3500-4BD01 is a 22 mm round metal actuator Ronis-key operated selector switch. It uses a Ronis lock with two keys and offers two switch positions (O and I) with momentary contact (lock number SB30). Designed for front-panel mounting in industrial controls, this compact operator enables keyed access to start/stop sequences or signal routing within a control circuit. The 22 mm format fits standard panel cutouts in Siemens automation installations, and the robust metal construction supports reliable operation in demanding environments. With two keys included, it provides secure operation by authorized personnel. Common applications include machine control panels, process selectors, and safety-related control paths where a keyed selector helps prevent unauthorized operation.