The Siemens 3RT1046-3BM40 is a SIRIUS S3-frame power contactor rated for motor switching up to 55 kW at 500 V in AC-3 duty and 25.4 kW at 690 V — that's the standard induction-motor start/run curve, so it handles most 50–75 kW-class pumps, fans, and compressors on common European 400 V networks with headroom. For reversing or inching applications, the AC-4 rating of 80 A at 400 V governs the contactor's ability to break stalled-rotor current repeatedly; that's the number to use when sizing for jogging or plugging duty, not the AC-3 figure. The S3 frame mounts on 35 mm or 75 mm standard DIN rail via the integrated snap-on foot, or can be screw-fastened to a backplate — the dual fastening method lets panel builders standardise on one contactor across both DIN-rail and bolted layouts. IP20 on the front with the cover or box terminal fitted means the contactor is touch-safe in a closed panel; the terminal body itself is IP00, so live parts are exposed until the enclosure door is shut — standard for panel-mount contactors.
Lifecycle and compliance — current production, documented
Substance prohibitance date of 05/01/2012 aligns with the EU RoHS recast (2011/65/EU) compliance horizon — the contactor meets RoHS and REACH material restrictions for European BOMs.
Termination and wiring — screw terminals, dual-wire capacity
Main current circuit uses screw-type terminals; the solid conductor range accepts 2x (0.25 to 2.5 mm²) for control wiring and 2x (10 to 50 mm²) for stranded power cables — the dual-wire capacity per clamp simplifies daisy-chaining or paralleling feeds without additional terminal blocks. The intermediate stranded range of 2x (2.5 to 16 mm²) covers the most common panel-building wire sizes for S3-frame motor circuits.
Switching performance — mechanical and electrical endurance
Maximum switching frequency varies by duty: 900 operations per hour at AC-1 (resistive loads), 850 at AC-3 (motor start/run), and 250 at AC-4 (reversing/inching) — the AC-4 limit reflects the higher thermal stress of breaking locked-rotor current.