What it is and what it does
The Siemens 3RT1036-1BW44 is a SIRIUS series power contactor, size S2, designed for switching motor loads in industrial control panels. It's a screw-type terminal unit rated for 22 kW at AC-2 duty on a 400 V line, and 41 A at AC-4 on the same voltage — the AC-4 figure is the one that governs reversing or inching duty, where the contacts make and break under full load current.
Mounting and panel fit
Snaps onto a 35 mm DIN rail per EN 50022, or can be screw-mounted. At 55 mm wide and 112 mm tall, it's a standard S2 footprint — side-by-side mounting is allowed, so you can gang several contactors without extra spacing. Depth is 179 mm, which matters when you're laying out gland plates or enclosure depths.
Ratings and what they mean for the buyer
The AC-2 rating at 400 V (22 kW) covers slip-ring motor starting; AC-4 at 400 V (41 A) is the one for plugging or inching — the hardest duty on the contacts. The 30 kW at 500 V and 11.4 kW at 690 V give you the range for 500 V or 690 V line supplies common in heavy industrial or mining. The front face carries IP20; the terminals are IP00, so they need to be inside a cabinet or shrouded.
Terminal specs and wiring
Main circuit terminals accept solid wire: 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²), max 2x (0.75 to 4 mm²). Stranded goes up to 2x (0.75 to 25 mm²). The minimum cross-section at 40 °C is 16 mm². Pollution degree 3 means it's rated for industrial environments with conductive dust or condensation.
Environmental and compliance
Operates from -25 to +60 °C; stores from -55 to +80 °C. RoHS compliance date is May 1, 2012 — it's RoHS compliant. The coil operates on 48 V DC with a pick-up time of 20 to 25 ms and arcing time of 10 to 15 ms.