The Siemens SIRIUS 3RT1034-1AH20 is a size S2 power contactor rated for 18.5 kW at 500 V under AC-3 duty, with a 10 kW rating at 690 V. It snaps onto a standard 35 mm DIN rail per EN 50022 and measures 55 mm wide, 112 mm tall, and 115 mm deep — a compact footprint for a S2 frame that leaves room for auxiliary blocks on the side, since side-by-side mounting is supported. AC-3 switching at 500 V is the headline motor-rating figure here — 18.5 kW tells you the contactor is sized for a 25 hp class induction motor on a 480 V line. The AC-2 rating of 15 kW at 400 V covers slip-ring or wound-rotor motor starts where the inrush is lower but the break current is sustained.
Termination and environment
Main circuit termination is screw-type terminals. Solid conductors accept 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or max 2x (0.75 to 4 mm²). Stranded conductors go up to 2x (0.75 to 25 mm²) — that 25 mm² top end covers the line-side feed for a full-rated motor circuit without needing a separate terminal block. IP20 on the front, IP00 at the terminals — the terminal area is live and needs finger-safe shrouding or a cover if the panel is accessible to operators. The 60 °C top end means it can sit next to a transformer or drive in a warm cabinet without derating the coil pickup — the coil hold-in is already specified for that band.