The 3RT1044-8BB40-0AB1: The 24 VDC coil draws 10 A at rated voltage, with a dropout threshold below 18 V. For DC switching, the contactor is rated 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, and 0.3 A at 220 V — the current drops as voltage rises due to arc extinction limits in DC circuits. On AC motor duty, the contactor handles 37 kW at 500 V and 18.6 kW at 690 V. AC-2 duty (slip-ring motors, wound-rotor) is rated 30 kW at 400 V; AC-4 duty (plugging, inching) is rated 55 A at 400 V. These are the ratings that govern real motor switching — not the AC-1 resistive maximum.
Mounting and Integration
Mounts via screw and snap-on onto 35 mm or 75 mm standard DIN rail. Side-by-side mounting is permitted, so panels can be densely packed without derating for heat buildup — verify the ambient stays within the -25 to +60 °C operating range. Enclosure rated IP00; IP20 on the front with cover or box terminal. The contactor body relies on the panel enclosure for dust protection. Screw-type terminals on the main current circuit accept 2x (0.25...2.5 mm²) solid or 2x (10...50 mm²) stranded. The control circuit terminals accept 2x (2.5...16 mm²) solid or stranded. Strip length and torque values follow standard Siemens practice for the S3 frame.
Lifecycle and Compliance
RoHS compliance is confirmed with a substance prohibition date of May 1, 2012, covering the standard EU RoHS directive. The part carries the SIRIUS brand designation and is designed to IEC/EN 60947-4-1 standards for contactors and motor starters. Pollution degree 3 rating means it is suitable for industrial environments with conductive pollution or dry non-conductive pollution that becomes conductive due to condensation — typical for control panels in factory floors, not for clean rooms or sealed HVAC.
Switching Performance
Arcing time is 10...15 ms, and the DC operating time (coil pull-in) is 14...20 ms. These timing figures matter for coordination in sequential switching or safety circuits where contactor overlap must be minimized. Maximum mechanical operating frequency is 10,000,000 cycles typical. Electrical switching rates: 1,000 cycles/hour at AC-1 and AC-3, 400 cycles/hour at AC-2, and 300 cycles/hour at AC-4. The AC-4 limit is the binding constraint for applications with frequent plugging or inching.