What it is and what it does
The Siemens 3RT1344-1AV00 is a SIRIUS S3 power contactor rated for motor switching at 42 kW at 230 V at 60 °C, with a rated operational voltage of 400 V at 50 Hz. The coil operating range spans 0.8 to 1.1 times the rated voltage at 50 Hz, which means the coil holds in reliably down to 320 V on a 400 V nominal system — a margin that matters when the bus sags under a large motor start. Its insulation voltage is rated at 1 000 V and surge voltage resistance at 6 kV. The contactor is rated for pollution degree 3.
Mounting and integration
Mounts via screw and snap-on onto 35 mm and 75 mm standard mounting rail — the snap-on feature speeds panel assembly when you are populating a row of SIRIUS gear. Side-by-side mounting is permitted, so you can gang multiple contactors without a mandatory gap, provided the ambient stays within the -25 to +60 °C operating range. The contactor measures 146 mm high by 93 mm wide by 139 mm deep. That 139 mm depth is the dimension to check against your enclosure back-panel clearance, especially if you are retrofitting into an existing cabinet where the gland plate or door-mounted devices limit reach. Front protection is IP20 with the cover or box terminal installed; the terminal itself is IP00. In a panel with IP54 or better overall rating, the IP20 front is adequate for finger-safe touch protection during commissioning.
Termination and wiring
Main current circuit uses screw-type terminals. Solid wire capacity covers 2x (0.5... 1.5 mm²), 2x (0.75... 2.5 mm²), and up to 2x (0.75... 4 mm²). Stranded conductors accept 2x (10... 50 mm²). Auxiliary and control circuits also terminate on screw-type terminals, with solid or stranded capacity of 2x (2.5... 16 mm²). This keeps the same tooling across both power and control wiring.
Switching performance and coordination
Mechanical endurance is rated at 10 000 000 operations typical — that is the mechanical life, not the electrical life under load. For resistive loads at AC-1, the maximum switching frequency is 1 000 cycles per hour, which is adequate for most conveyor and pump cycling but not for high-speed indexing applications. Operating time on AC is 10 to 25 ms, with arcing time of 10 to 15 ms. The arcing time is the interval the contacts carry current after the coil drops out; for Type 2 coordination (no-weld requirement), the evidence specifies a fuse of 125 A gL/gG. That fuse rating is the one to coordinate with upstream protection if you are designing for selectivity. DC switching capacity is derated significantly from the AC ratings: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V, and 6 A at 230 V (likely AC-3 or AC-4 duty at that voltage). The 400 V DC rating is 3 A. For any DC load above these levels, you would need a DC-rated contactor or a series arc-suppression network.
Lifecycle and compliance
Storage temperature range is -55 to +80 °C, which exceeds the operating range — that limit governs handling during shipping and warehousing, not running conditions.