What It Is and Where It Fits
The Siemens 3RT1045-1BE40 is a SIRIUS power contactor in the S3 frame size, designed for switching motor loads in industrial control panels. It mounts via screw or snap-on onto 35 mm or 75 mm standard DIN rail, which means it drops into a standard panel layout without custom bracketing.
Key Ratings and What They Mean for Your BOM
The headline motor-switching rating is 37 kW at 400 V under AC-2 duty — this is the category for slip-ring motors, so the contactor is sized for starting and stopping those loads at that power level. For AC-4 duty (plugging, inching, reversing), the rated operational current is 66 A at 400 V, which governs the thermal stress during frequent reversals. The main current circuit uses screw-type terminals, which accept solid conductors from 0.5 mm² up to 4 mm² (two per clamp) and stranded conductors up to 50 mm². That covers the range from control wiring to motor power tails without needing adapters. Front protection is IP20 with the cover or box terminal fitted; the terminal itself is IP00. Degree of pollution 3 means it's rated for conductive pollution environments typical in industrial enclosures — no special derating needed for dusty or humid panel air.
Lifecycle and Sourcing Reality
RoHS compliance is documented with a substance prohibition date of May 1, 2012, covering the EU directive scope. No other compliance flags (UL, CSA, CE) are explicitly listed in the spec record, but the SIRIUS series typically carries those marks — verify against your local panel certification requirements.
Panel Integration Notes
Dimensions are 146 mm high, 70 mm wide, 152 mm deep — the S3 frame fits a standard 70 mm wide DIN-rail footprint. Side-by-side mounting is permitted, so you can gang multiple contactors on the same rail without derating for heat buildup, as long as the ambient stays within -25 to +60 °C operating range. Mechanical life is typical 10 million operations; the switching frequency varies by duty: up to 1,000 cycles/hour under AC-3, 900 under AC-1, 400 under AC-2, and 300 under AC-4. For high-cycle applications like conveyor indexing, the AC-3 figure is the one that governs contactor wear.