What it is and where it lands
The Siemens 3RT2045-1NB34 is a SIRIUS power contactor in the S3 frame size, designed for switching motor loads and resistive circuits in industrial control panels. It uses a 20-33 VDC coil with screw-type terminals and mounts via screw fixing or snap-on onto 35 mm DIN rail per DIN EN 60715, with mounting position flexibility of ±180° rotation and ±22.5° tilt on vertical surfaces.
Key ratings and what they mean for your panel
The AC-3 switching rate of 1 000 cycles per hour tells you this contactor is rated for frequent motor starting — typical for conveyor drives, pumps, and compressors in cyclic duty. AC-4 maximum at 300 cycles/h covers plugging and inching applications where the contactor makes and breaks under full load current. AC-1 resistive switching at 900 cycles/h suits heater banks or lighting loads. Coil inrush peaks at 6.5 A, then holds at 3.5 VA at both 50 and 60 Hz. The pickup and dropout times are symmetrical at 38-57 ms for both AC and DC operation, which simplifies timing coordination in sequential start schemes. Auxiliary contacts are built in, rated at 6 A at 24 V, 2 A at 48 V and 60 V, and 1 A at 110 V — these cover control-circuit interlocking and status feedback without needing a separate auxiliary block.
Panel integration — DIN rail, wiring, and clearances
At 70 mm wide, 140 mm tall, and 195 mm deep, the S3 frame occupies a standard 4-module width on 35 mm DIN rail. Minimum clearances: 10 mm upwards, 10 mm downwards, 20 mm forwards, and 10 mm at the sides — plan your enclosure depth accordingly. Main circuit terminals accept stranded conductors from 6 to 70 mm², while solid or stranded control wiring from 2.5 to 16 mm² fits the coil terminals. For auxiliary circuits, two conductors per terminal are allowed: 2x (0.5-1.5 mm²) or 2x (0.75-2.5 mm²). Operating temperature range is -25 to +60 °C; storage range extends from -55 to +80 °C. The contactor is rated for 10 million mechanical operations typical, with arcing time of 10-20 ms on the main contacts.