The Siemens 3RT2517-1BG40 is a SIRIUS contactor in size S00 – a compact 45 mm wide frame with a depth of 73 mm and height of 57.5 mm that snaps onto a 35 mm DIN rail. Screw terminals accept two conductors each in three cross-section ranges: 0.5–1.5 mm², 0.75–2.5 mm², and up to 4 mm² solid/stranded. That means you can wire a motor circuit with heavier gauge without needing a bigger contactor. Mechanical life is rated at 30 000 000 cycles, and the contactor can switch at up to 10 000 1/h (AC) – 1 000 1/h in AC-1 resistive load. It also carries an auxiliary switch.
No extra clearance needed upwards, forwards, or backwards – zero mm. Side clearance required is 6 mm for side-by-side mounting.