Key Ratings and What They Mean for Fit
The 3RT1044-3BM40: The AC-3 rating of 37 kW at 500 V is the headline motor-switching capacity — it tells you the contactor can handle a 3-phase induction motor of that power under normal starting conditions (6–8x inrush, switching off at rated current). The AC-4 rating of 55 A at 400 V is the more demanding duty class: it applies when the contactor makes and breaks stalled-rotor current, so if your application involves frequent reversing or inching, this 55 A figure is the one to size against, not the AC-3 kW number. The AC-1 maximum operating frequency of 1 000 switching cycles per hour and AC-4 maximum of 300 cycles per hour set the thermal limits for repetitive operation — useful for high-cycle conveyor or press applications. The auxiliary contact ratings span from 10 A at 24 V up to 6 A at 230 V and 3 A at 400 V, covering a range of PLC and relay interface voltages. The mechanical service life is 10 000 000 operating cycles typical, which is the benchmark for the SIRIUS platform.
Environmental and Installation Conditions
The contactor is rated for a degree of pollution 3 (conductive pollution or dry non-conductive pollution that becomes conductive due to condensation), which is standard for industrial control panels not in sealed enclosures. Operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C. The enclosure protection is IP20 on the front with the cover or box terminal fitted; the terminal itself is IP00, meaning the wiring compartment requires the panel's own IP rating. Side-by-side mounting is permitted without derating, which simplifies panel layout. Wire sizes: solid conductors accept 2x (0.25... 2.5 mm²) for control wiring, while the main power terminals accept stranded 2x (10... 50 mm²) or solid/stranded 2x (2.5... 16 mm²).