What it is and what it does
The Siemens 3RT1055-6XB46-0LA2 is a SIRIUS power contactor in size S6, designed for switching motor loads and resistive circuits in industrial control panels. It carries a 24 V DC coil, screw-fixing mounting, and an integrated auxiliary switch block.
Key ratings and what they mean for fit
The 24 V DC coil picks up at 70% of rated voltage (about 16.8 V) and drops out at 125% (30 V), so it holds in during a sag but releases cleanly on overvoltage. The DC switching time of 80 to 90 ms and arcing time of 10 to 15 ms matter for coordinating with upstream protection — the contactor clears its arc before a fast semiconductor fuse would react. Mechanical life is rated at 10 million operations typical. The auxiliary contacts handle 6 A at 24 V DC, derating to 0.9 A at 125 V DC — enough for PLC inputs or relay coils on the same control voltage. Operating temperature range of -40 to +70 °C and storage range of -55 to +80 °C cover cold storage rooms and hot panel interiors without derating the coil.
Switching frequency by duty class
Maximum switching rates are duty-dependent: 800 ops/h in AC-1 (resistive), 750 ops/h in AC-3 and AC-3e (standard motor starting), 300 ops/h in AC-2 (slip-ring motors), and 130 ops/h in AC-4 (plugging/inching). For DC loads: 400 ops/h in DC-1, 350 ops/h in DC-3 and DC-5.
Mounting and clearances
Mounts via screw fixing with a single 9 mm hole. The enclosure needs 10 mm clearance upwards, downwards, and to the sides, plus 20 mm forwards for arc venting. The mounting surface can be vertical with ±90° rotation and ±22.5° tilt front-to-back. Dimensions are 172 mm high, 120 mm wide, 170 mm deep — size S6 frame. Wire terminals accept solid or stranded conductors: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or max 2x (0.75 to 4 mm²).