The Siemens SIRIUS 3RT1025-1AN24 is a size S0 power contactor rated for motor switching at 7.5 kW at 400 V AC-3 (50/60 Hz) and 11 kW at 690 V.
Main contact wiring accepts 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or max 2x (0.75 to 4 mm²) solid or stranded; auxiliary side takes 2x (1 to 2.5 mm²) or max 2x 10 mm². AWG equivalents: main 2x (16 to 12), 2x (14 to 10), 1x 8. Side-by-side mounting is permitted — no derating gap required, but the 6 mm side clearance to adjacent components is the minimum for heat dissipation. Depth of 140 mm and height of 85 mm mean it clears most 200 mm deep enclosures, but check gland-plate protrusion if the contactor sits near the back wall. The S0 footprint is shared across the SIRIUS 3RT1 family, so a swap to a higher-rated sibling keeps the same DIN rail drilling.
Type 2 coordination calls for 25 A. That's the short-circuit protection the contactor needs to survive a fault without welding — spec the fuse downstream accordingly. Mechanical life is typical 10 million operations; the AC-4 rating at 400 V is 15.5 A for heavy inching or plugging duty.