The Siemens 3RT1015-1AR01 is a SIRIUS power contactor in the Size S00 frame — the smallest footprint in the family at 45 mm wide, 57.5 mm tall, 72 mm deep.
Rated 4 kW at 690 V AC-3 and 3 kW at 400 V AC-2, so it handles standard three-phase induction motors in that power band — think small pumps, fans, compressors. For resistive loads (AC-12), it carries 10 A. The coil operates on 24 V DC with a 10 A rated value — that's the inrush, not the hold; the actual sealed draw is lower.
Surviving the panel environment
Pollution degree 3 — conductive dust and humidity are expected, so the 6 mm side clearance and IP20 finger-safe front matter for creepage and safety. Altitude rated to 2000 m; no derating needed at typical plant elevations.
Terminal wiring and coordination
Screw terminals accept 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or up to 2x 4 mm². AWG equivalents: 2x (20-16), 2x (18-14), 1x 12. Type 2 coordination calls for a 20 A gL/gG fuse; Type 1 allows 35 A. That's the short-circuit protection you need to specify alongside the contactor — don't let the panel builder guess.