What this GM-SET contactor is
The Siemens 3RA9012-5AE05 is a GM-SET contactor assembly — a 3-pole, non-reversing contactor rated 24 A, with a 1NO-3NC auxiliary contact block and integral surge suppression built in. The GM-SET designation means it ships as a pre-assembled unit: contactor, aux contacts, and surge suppressor on one DIN-rail mountable base, ready to wire into a motor starter or general switching circuit.
The 1NO-3NC auxiliary configuration gives you one normally-open and three normally-closed mirror contacts. That matters for feedback wiring: the NO picks up the 'run' status to a PLC input, while the three NC contacts can seal in a safety chain or interlock multiple starters. The integral surge suppression (varistor or RC snubber across the coil) means you don't need an add-on suppressor module — it's already in the package, saving a DIN-rail position and one wiring step.