What it is and what it does
The Siemens 3RT1034-1BF40 is a SIRIUS S2-frame power contactor for switching motor loads in control panels. It mounts on a 35 mm DIN rail per EN 50022, with screw terminals for the main circuit and a 110 V DC coil. Rated for AC-2 duty at 15 kW and AC-4 reversing duty at 29 A, both at 400 V, this contactor handles slip-ring motor starting and reversing applications where frequent jogging or inching is required. The front face carries an IP20 rating, suitable for enclosed panel installation where accidental finger contact is prevented. The terminals themselves are IP00 — no touch protection at the wiring point, so panel builders should plan for terminal shrouds or additional guarding.
Sourcing and lifecycle
RoHS compliance date is noted as May 1, 2012, and the part carries a substance prohibitance declaration for REACH compliance.
Panel fit and wiring
At 55 mm wide and 130 mm deep, the S2 frame occupies one standard DIN-rail module position. Side-by-side mounting is permitted — no derating required for adjacent contactors at rated current. Main circuit terminals accept solid conductors up to 2x 4 mm² or stranded up to 2x 25 mm². The coil terminals accept 2x 0.5–1.5 mm² solid or 2x 0.75–2.5 mm² stranded. Strip length for screw terminals follows standard practice — 10–12 mm for the larger conductors. Operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C. Pollution degree 3 means the contactor is rated for industrial environments with conductive pollution or dry non-conductive pollution that becomes conductive due to condensation.
Coil and switching characteristics
The 110 V DC coil draws 10 A at 24 V inrush and 1 A at 110 V holding. Dropout time is 20–30 ms, arcing time 10–15 ms — fast enough for most safety circuits but verify coordination with upstream overcurrent devices. Mechanical life is rated at 10 million operations typical. Electrical life depends on duty: 1,200 ops/hour at AC-1, 1,000 at AC-3, 750 at AC-2, and 250 at AC-4 — the reversing duty class limits switching frequency to about 4 operations per minute.