The Siemens 3RT1034-1BM40 is a SIRIUS power contactor in the S2 frame size, rated for 18.5 kW at 500 V AC-3 duty and 10 kW at 690 V. It switches motor loads in control panels and mounts on a 35 mm DIN rail per EN 50022, with screw-and-snap-on fastening. The IP20 front enclosure means the terminals are protected against finger contact in the panel, while the connection side is IP00 — standard for panel-mount contactors where the wiring compartment is enclosed by the cabinet.
Ratings and what they mean for fit
The 18.5 kW at 500 V AC-3 rating is the motor-switching figure that governs most selections — it tells you the contactor can handle the inrush and breaking of a squirrel-cage motor up to that power. At 400 V AC-2 (slip-ring motors), it is rated for 15 kW. The AC-4 rating of 29 A at 400 V covers plugging and inching duty, where the contactor makes and breaks stalled-rotor current. Maximum operating rate is 1,000 operations per hour in AC-3, 250 in AC-4 — the lower figure reflects the heavier arc duty in reversing or jogging applications. Coil options: the 1BM40 variant carries a 220 V AC coil (50/60 Hz). Pickup voltage is 0.8 x rated (176 V), dropout below 0.55 x rated (121 V). Dropout time on DC is 20 to 30 ms; arcing time is 10 to 15 ms. The 24 V DC coil current is 10 A — this is the holding current, not the pickup surge. Wire range: solid conductors from 2x 0.5 mm² up to 2x 4 mm²; stranded up to 2x 25 mm². At 40 °C ambient, the minimum permissible cross-section is 16 mm² for the main circuit — this derating matters when the panel runs hot.
Compliance and approvals
Substance prohibitance (RoHS) compliance date is May 1, 2012 — the contactor meets RoHS and REACH requirements. Pollution degree 3 per IEC 60947-1, meaning it is rated for industrial environments with conductive pollution. Storage temperature range is -55 to +80 °C; operating ambient is -25 to +60 °C.
Mounting and integration
Width is 55 mm, height 112 mm, depth 130 mm. Side-by-side mounting is permitted — no gap required between contactors on the DIN rail, which saves panel width. Screw-type terminals for the main circuit; the control circuit uses the same screw clamp. The S2 frame is the standard size for this power band; it fits the same footprint as other SIRIUS S2 contactors and accessories (auxiliary contact blocks, surge suppressors, mechanical interlocks).