What the MTBF and duty cycle tell you about this SIRIUS S3
The 3RT2045-1SB30: The MTBF is 52 a — that's the mean time between failures for the contactor under the defined operating conditions, not a service life guarantee. For a Size S3 frame in the SIRIUS line, that figure reflects the reliability Siemens targets for high-cycle motor-starting applications. Rated for 1 000 switching cycles per hour in AC-3 duty (motor starting) and the same for AC-3e. The maximum in AC-4 (plugging/reversing) drops to 300 cycles/h — the arcing during inrush under those loads wears the contacts faster. If your application involves frequent reversing or inching, budget for the lower duty class.
Coil draw and control circuit fit
Coil inrush peak is 2 A; the holding current at 24 V rated value is 10 A, dropping to 2 A at 48 V and 60 V. The sealed-state draw is much lower than the inrush — a PLC output driving this coil needs to handle the 2 A peak, not just the holding current. The coil terminal type is screw-type terminals, solid or stranded wire 2x (0.5... 1.5 mm²) or 2x (0.75... 2.5 mm²). Operating range for the coil is 21... 33 V rated value — that's the control voltage window. The pick-up voltage (initial value) is 0.8 × rated, so at 24 V nominal it pulls in at about 19.2 V. Keep the supply rail above that threshold even under brownout conditions.
Mounting and clearance for panel layout
Mounts on 35 mm DIN rail per DIN EN 60715 with both screw and snap-on fastening. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward — you can orient it to fit the cable entry direction. Required clearances: 10 mm upwards, 10 mm downwards, 20 mm forwards, 10 mm at the side. That's the minimum air gap for heat dissipation and arc quenching. Dimensions: 152 mm depth × 70 mm width × 140 mm height. The Size S3 frame is one of the larger contactor sizes in the SIRIUS family — plan for the panel depth accordingly. Conductor cross-sections: solid 2.5... 16 mm², stranded 6... 70 mm² for the main circuit.