Active production — no lifecycle concern for this BOM line
The 3RT2018-1UB41: The SIRIUS S00 platform is Siemens' mainstream small-contactor family, so accessory compatibility (auxiliary blocks, surge suppressors, busbar bridges) is stable across production lots.
S00 frame — 45 mm width governs DIN-rail density
The S00 frame is the smallest Siemens SIRIUS contactor footprint: 45 mm wide, 73 mm deep, 58 mm tall. These are the minimum air gaps to adjacent metalwork or enclosure walls — ignore them and the arc chute cannot vent, which raises the risk of phase-to-phase flashover during a fault interruption.
This lets you daisy-chain the control supply through the auxiliary contacts without a separate terminal block — a time-saver on a crowded panel. The wire range covers both control-circuit signal wiring (0.5 mm²) and power-circuit motor leads (4 mm²). For a 2.5 mm² motor feed, you land one conductor per clamp; the second clamp position stays available for a parallel feed or a test lead.
24 V coil — DC dropout delay 7 to 13 ms
The coil is rated 24 V (DC or AC, the spec does not distinguish frequency, so treat it as 24 V DC for PLC-driven applications). The DC dropout delay is 7 to 13 ms — the interval between coil power loss and main-contact opening. In a safety circuit, this window sets the minimum off-delay the downstream guard logic must tolerate before confirming the load is disconnected. Arcing time under AC load is 10 to 15 ms. This interval governs the zero-crossing hold-off: the arc must extinguish before the contact gap recovers dielectric strength. For a 50 Hz system (10 ms half-cycle), the arc typically clears within one half-cycle; at 60 Hz (8.33 ms half-cycle), it may stretch into the next half-cycle, so the contactor's AC-3 electrical life should be derated for 60 Hz operation.
For a 24 V DC PLC input, the 10 A rating is far above the signal current (typically 5 to 10 mA), so contact wetting current is not a concern. For a 400 V AC control circuit, the 3 A rating limits the number of parallel contactor coils you can drive — each SIRIUS S00 coil draws about 4 VA inrush, so you can drive roughly 20 coils before hitting the auxiliary contact's make/break capacity. The auxiliary contact also carries a 2 hp rating at 230 V (single-phase motor load). This is the maximum motor size the auxiliary contact can switch directly — useful for a small fan or pump interlock, but for anything larger, use the main poles.
Mechanical endurance — 30 million operations typical
The mechanical endurance is 30 million operations typical. Under AC-3 duty (motor starting, switching off running motors), the maximum switching rate is 750 operations per hour; at AC-4 duty (plugging, inching), the rate drops to 250 operations per hour. For a conveyor line cycling once per minute (60 ops/hour), the mechanical life exceeds 30 years — the electrical life under load will be the limiting factor, not the mechanism. In an unheated enclosure in a northern climate, the -25 °C lower limit means the contactor will pick up reliably at cold start; below that, the coil's magnetic circuit may not generate enough force to close the main contacts against spring pressure.