What this pushbutton does in a motor starter line
The Siemens 3RA9012-5BQ42 is a GM-SET pushbutton assembly — a mushroom-head, illuminated amber, push-pull operator with 1 normally-open and 3 normally-closed contacts, terminated via Cage Clamp connection. It is catalogued under Motor Starters, meaning it serves as a control-station component for starting, stopping, or emergency-off functions on a motor circuit.
Contact configuration and termination
The 1NO + 3NC contact arrangement gives you one make contact for a start signal and three break contacts for redundant stop or safety interlock paths — typical for an E-stop station where multiple NC channels feed into a safety relay or PLC input. Cage Clamp termination means the wires are held by a spring clamp, not a screw — no re-torquing after thermal cycling, and the connection stays gas-tight under vibration common on a panel door or machine frame.