What it is and what the ratings mean
The Siemens 3RT2346-1AV00-4AA0 is a SIRIUS power contactor rated for AC-3 motor duty at 95 A, which is the current it can switch for standard three-phase squirrel-cage motors during starting and running. That 95 A AC-3 rating translates to a 45 kW motor on a 400 V three-phase line — the spec that tells you this contactor handles a 45 kW load in a typical European 400 V industrial panel. The 4-pole configuration means it switches all three phases plus one additional pole, often used for a separate control circuit or a second load. The coil is 400 V AC at 50 Hz, so it pulls in and holds on a standard European line voltage. Auxiliary contacts are 1 NO and 1 NC — enough for feedback to a PLC or a holding circuit without needing a separate auxiliary block. Terminals are screw type, which is the workhorse connection for most panel builders; no special tooling required.
Where it fits in the panel
Size S3 means it occupies a specific footprint on the DIN rail or mounting plate — roughly the 174 x 146 x 137 mm package dimensions. That's a common size for 95 A contactors in the SIRIUS family, so it swaps into existing S3 cutouts and busbar systems without re-drilling. Screw terminals accept standard ring or fork lugs; torque specs are on the nameplate.