What it is and where it fits
The Siemens SIRIUS 3RT1034-3XF00-0GA0 is an S2-size power contactor from the SIRIUS family, designed for switching motor loads in industrial control panels. Its AC-2 rating at 400 V is 15 kW, which covers the typical duty cycle for slip-ring motors or reversing applications where the contactor makes and breaks under load at reduced current. The AC-4 rating at 400 V is 29 A, covering plugging and inching operations where the contactor handles full locked-rotor current. It mounts via screw and snap-on onto a 35 mm DIN rail per DIN EN 50022, and side-by-side mounting is allowed, so you can pack multiple units into a panel without derating for heat buildup.
Key ratings and what they mean for your BOM
The 15 kW AC-2 at 400 V rating tells you this contactor is sized for moderate motor loads in applications where the switching frequency is moderate — up to 750 operations per hour at AC-2. The AC-4 rating of 29 A at 400 V covers the worst-case inching duty, but at a lower maximum operating rate of 250 cycles per hour. If your motor is a standard squirrel-cage induction motor starting across the line (AC-3 duty), the contactor handles up to 1 000 operations per hour, but the AC-3 kW rating at 400 V is not listed in this evidence — you'd need to confirm that from the full datasheet. The operating temperature range is -25 to +60 °C, and the degree of pollution is 3, meaning it's rated for industrial environments with conductive dust or moisture. The front is IP20, so finger-safe when installed in an enclosure; the terminals are IP00, so they require a panel or enclosure to prevent accidental contact.
Terminal and wiring details
The main current circuit uses screw-type terminals. For solid conductors, each terminal accepts 2x (0.25 to 2.5 mm²). For stranded conductors, the range is 2x (0.75 to 25 mm²) for the main circuit, and 2x (0.75 to 16 mm²) for the auxiliary circuit. That covers most panel wiring from control signal leads up to motor feeder cables. The contactor dimensions are 55 mm wide, 142 mm high, and 130 mm deep — a compact S2 footprint that fits standard 55 mm-wide DIN-rail slots.