SIRIUS Size S3 power contactor — 42 kW at 230 V
The Siemens SIRIUS 3RT1344-1AL20 is a Size S3 power contactor rated for 42 kW at 230 V, 50/60 Hz, with an insulation voltage of 1000 V. It mounts on 35 mm or 75 mm standard DIN rails via screw or snap-on fastening, fitting into a 93 mm wide by 146 mm high by 139 mm deep envelope — a compact footprint for a contactor that handles motor loads up to this power class.
Coil and contact ratings — what drives the fit
The coil draws 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, and 0.3 A at 220 V — these are the holding currents, not the inrush. The main contacts are rated for 42 kW at 230 V (AC-3 duty, the motor-switching curve), so this contactor is sized for a 3-phase induction motor in that power band. At 400 V the contact rating drops to 3 A, reflecting the AC-1 resistive load curve.
Terminal wiring and environmental limits
Main-circuit terminals accept solid conductors from 0.5 to 4 mm² (two per clamp) and stranded from 10 to 50 mm² (two per clamp), with AWG equivalents from 10 to 1/0.