What This Part Is and Where It Goes
The Siemens SIRIUS 3RT2027-2DB40 is a size S0 power contactor with a 24 VDC coil terminated via spring-type terminals. It's designed for screw and snap-on mounting onto 35 mm DIN rail per DIN EN 60715, so it drops into a standard panel enclosure without extra bracketry. The coil holds at 24 VDC nominal with an operating range of 0.8 to 1.1 times rated value. Below that dropout threshold, the contactor releases cleanly. Switching frequency depends on duty: 1 000 cycles/hour max for AC-1 resistive loads, 750 cycles/hour for AC-2 and AC-3 motor starting, 250 cycles/hour for AC-4 plugging/reversing, and 750 cycles/hour for AC-3e. Match your load profile to the right column — AC-4 at 250 ops/h is the limiter for frequent jogging or inching.
Mounting and Integration Notes
The S0 frame measures 45 mm wide, 102 mm tall, and 107 mm deep — a compact footprint that leaves room for auxiliary contact blocks or overload relays on the same DIN rail. Clearance: 10 mm upward, 10 mm forward, 10 mm downward, and 6 mm at the side. That's tight enough for dense panel layouts but leaves enough air for arc quenching. Mounting position is flexible: +/-180° rotation on a vertical surface, plus +/-22.5° tilt forward/backward. Useful when the panel layout forces an odd orientation — the contactor doesn't care. Wire sizes: solid or stranded 1 to 10 mm² for main power connections, and 2x (0.5 to 2.5 mm²) for auxiliary circuits. The spring-type terminals on the coil side hold firm without re-torquing — set it and forget it.
Lifecycle and Sourcing Reality
Mechanical life is rated at 10 000 000 operations typical — that's a decade-plus in most cycling applications before the spring stack or armature wears out. Electrical life depends on load and switching frequency, but the mechanical endurance gives you headroom for high-cycle conveyor or pump starts.
Environmental and Compliance
Operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C. That covers most indoor panel environments and unheated warehouses. No IP rating listed in the evidence, so treat it as open-frame — mount inside a sealed enclosure if washdown or dust is present. The auxiliary switch is included (yes), so you get a built-in N/O or N/C contact for status feedback or interlocking without adding a separate block. Arcing time is 10 to 10 ms — consistent, repeatable quenching across the load range.