It mounts on 35 mm or 75 mm standard DIN rail using screw or snap-on fastening, so it fits into a typical panel layout without special bracketing. For AC-4 duty — plugging and inching of squirrel-cage motors — it carries 55 A at 400 V. The coil is 230 V at 50 Hz, with an operating range of 0.8 to 1.1 times the rated voltage, so it holds in during a brownout down to about 184 V.
The 3RT1044-1AP04 accepts solid conductors in two ranges: 2x (0.5 to 1.5 mm²) and 2x (0.75 to 2.5 mm²), with a maximum of 2x (0.75 to 4 mm²). For stranded conductors, it takes 2x (10 to 50 mm²). The terminal is rated IP00 at the connection point, but the front of the contactor carries IP20 with a cover or box terminal, so it's touch-safe once installed in an enclosure. Side-by-side mounting is allowed with no derating mentioned, which saves rail space in a multi-contactor group. The contactor measures 146 mm high by 70 mm wide by 188 mm deep. That depth is worth checking if you're fitting it into a shallow enclosure — 188 mm is deeper than a typical IEC contactor of this frame size, so leave clearance for the arc chamber and wiring space behind the terminals.
Duty cycle and mechanical life
Maximum switching rates vary by duty: 1,000 operations per hour for AC-1 (resistive) and AC-3 (normal motor start/run), 400 ops/h for AC-2, and 300 ops/h for AC-4. For the auxiliary contact side, the 24 V rated current is 10 A, dropping to 0.3 A at 220 V and 3 A at 400 V — enough for pilot duty on a PLC input or relay coil.