It carries three normally-open main contacts and a 42 VDC coil that draws 5.4 W on both closing and holding — a single-wattage coil, so the control transformer sees a steady load.
The 3RT1025-3BD40 is rated for motor switching in AC-3 duty (starting and disconnecting squirrel-cage motors under load). At 400 V it handles 7.5 kW; at 500 V, 10 kW; at 690 V, 11 kW. In AC-2 duty (slip-ring motors) at 400 V it also carries 7.5 kW.
Panel fit and wiring constraints
The contactor body is 45 mm wide, 85 mm tall, and 100 mm deep — a compact S0 footprint that leaves room for auxiliary contact blocks on the side (6 mm clearance needed). The screw-type main terminals accept 2x (0.25 to 2.5 mm²) solid, 2x (1 to 2.5 mm²) stranded, or up to 2x 10 mm² single-core. For AWG, that's 2x (16 to 12) solid or 2x (14 to 10) stranded, with a maximum single 8 AWG.
The contactor itself has a mechanical life of 10 million operations typical — that's the unloaded switching endurance; electrical life depends on the load current and duty cycle.