The Siemens 3RT1025-1AF04 is a SIRIUS power contactor in size S0, with three normally-open main contacts and screw-type terminals for the main current circuit. It mounts on a 35 mm DIN rail per DIN EN 50022, either snapped on or screwed, fitting a standard panel enclosure. Rated at 7.5 kW in AC-2 duty at 400 V, this contactor handles wound-rotor motor loads up to that power. For AC-4 reversing or plugging duty at 400 V, the operating current is 15.5 A. The 690 V rating reaches 11 kW, and at 500 V it delivers 10 kW. The 45 mm width and 140 mm depth fit into the S0 frame footprint, leaving room alongside for auxiliary contact blocks or overload relays in the same DIN-rail row.
Terminal capacity and wiring
Main contact screw terminals accept solid conductors: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or up to 2x (0.75 to 4 mm²). For stranded or multi-stranded wire, the range is 2x (1 to 2.5 mm²), 2x (2.5 to 6 mm²), or max 2x 10 mm². AWG equivalents for the main contacts are 2x (16 to 12), 2x (14 to 10), or 1x 8. For type 2 coordination, the required fuse is gL/gG 25 A; for type 1 coordination, gL/gG 63 A. This determines the short-circuit protection upstream.
Environmental and mounting constraints
Operating temperature range is -25 to +60 °C during operation. The maximum operating altitude is 2 000 m. Pollution degree 3 means it tolerates conductive pollution in industrial environments. The front of the terminal has IP20 protection; the terminal itself is IP00. Side-by-side mounting is allowed with a 6 mm gap to the side. The coil operates at 50 Hz with a voltage range of 0.8 to 1.1 times the rated value.