What this SIRIUS S2 contactor carries
The Siemens 3RT1034-1BM44 is a SIRIUS-brand power contactor in size S2, rated to switch motor loads up to 18.5 kW at 500 V in AC-3 duty or 10 kW at 690 V. Coil draws 10 A at 24 V DC; the contactor picks up in 20 to 30 ms DC and arcs in 10 to 15 ms. Mechanical life sits at a typical 10 million operations, with AC-3 switching frequency up to 1 000 cycles per hour.
Panel fit and wiring constraints
At 55 mm wide and 112 mm tall, the S2 frame leaves room for side-by-side mounting — the datasheet explicitly allows zero-gap adjacency. Depth reaches 179 mm, so factor that into gland-plate clearance and door swing on shallow enclosures. Main circuit terminals accept stranded wire from 2x 0.75 mm² up to 2x 25 mm², or solid/stranded 2x 0.75 to 16 mm². At 40 °C ambient, the minimum permissible conductor is 16 mm² — that's the thermal derating floor, not a suggestion.
Duty-cycle reality check
The AC-1 resistive load rating hits 1 200 cycles/hour, but AC-4 (plugging/reversing) drops to 250 cycles/hour — that's the mechanical limit under inrush stress. For motor starting (AC-3), 1 000 cycles/hour is the ceiling; don't push beyond it on frequent-start conveyors. DC switching ratings are modest: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V. If you're breaking DC motor fields or solenoid valves, verify the load falls under these curves — the contactor isn't a DC load-break specialist.