What this contactor is and what it switches
The Siemens 3RT1034-3BW40 is a SIRIUS power contactor in the Size S2 frame, designed for switching three-phase motor loads and resistive loads in industrial control panels. Its AC-3 rating of 18.5 kW at 500 V means it handles standard squirrel-cage motors up to that power — the typical duty for conveyors, pumps, and fans. The AC-4 rating of 29 A at 400 V covers reversing and plugging duty where the contactor makes and breaks stalled-rotor current. AC-2 at 400 V is rated 15 kW, covering slip-ring motor starting. Main circuit connections use screw-type terminals, accepting solid conductors up to 2x 2.5 mm² or stranded up to 2x 25 mm². The contactor mounts via screw and snap-on onto 35 mm DIN rail per EN 50022. Side-by-side mounting is permitted, which saves panel width when ganging multiple contactors — no required air gap between units.
Environmental and compliance data
Operating temperature range is -25 to +60 °C; storage range extends from -55 to +80 °C. Pollution degree 3 per IEC 60947-1 — suitable for industrial environments with conductive contamination. The contactor carries a RoHS substance prohibition date of 05/01/2012, indicating compliance with the EU RoHS directive. Front-of-device protection is IP20; the terminal area is IP00 (requires enclosure protection).
Coil and auxiliary ratings
The coil circuit is rated 48 V. Switching times: DC operate 20...30 ms, arcing time 10...15 ms. Auxiliary contact ratings at 24 V: 10 A; at 60 V: 2 A; at 110 V: 1 A; at 220 V: 0.3 A; at 230 V: 6 A; at 400 V: 3 A. Mechanical life of the contactor typical is 10 million operations. Maximum switching frequency varies by duty: AC-1 resistive loads up to 1,200 cycles/hour, AC-2 at 750, AC-3 at 1,000, AC-4 at 250 cycles/hour.