The Siemens 3RT1035-1AQ20 is a SIRIUS S2 power contactor built for switching motor loads in control panels. It carries a 24 VDC coil rated at 10 A, and is sized for 18.5 kW at AC-2 duty on 400 V or 11.4 kW at 690 V. Screw-type terminals on the main circuit accept stranded wire up to 2x 25 mm², and the contactor snaps onto a standard 35 mm DIN rail per EN 50022.
What the ratings mean for fit
The AC-2 rating at 400 V (18.5 kW) is the one that governs motor switching for slip-ring or wound-rotor motors — common on conveyors and hoists where starting current stays moderate. The 690 V rating (11.4 kW) covers line-to-line loads on 690 V systems, typical in European industrial networks. Coil hold is at 24 VDC nominal; the 10 A rating at that voltage means the coil draws about 0.42 A steady-state, so a standard 24 VDC power supply with 1 A per contactor leaves headroom. Operating temperature spans -25 to +60 °C, which covers most unventilated panel environments. Storage range of -55 to +80 °C means it survives cold shipping and hot warehouse racks without issue. The IP20 on the front and IP00 at the terminals means the contactor is meant for enclosed panels — not for washdown or outdoor exposure.
Mounting and wiring
Fastens with screw or snap-on onto 35 mm DIN rail per EN 50022. Width is 55 mm, depth 115 mm, height 112 mm — fits a standard S2 footprint. Side-by-side mounting is allowed, so you can gang multiple contactors without a gap. Screw terminals accept solid wire from 0.5 mm² up to 4 mm² (two per clamp) and stranded from 0.75 to 25 mm² (two per clamp). Strip length for stranded is roughly 10–12 mm depending on ferrule; the 2x 25 mm² capacity means you can parallel feeds for higher current.