The Siemens 3RT1025-3AN20 is a SIRIUS power contactor in the S0 frame size, rated for motor switching duty at 7.5 kW under AC-2 at 400 V and 15.5 A under AC-4 at 400 V. The main current circuit uses screw-type terminals, accepting 2x (0.25...2.5 mm²) solid or 2x (1...2.5 mm²) stranded, up to 2x 10 mm² maximum.
For short-circuit protection, the coordination requirements are specified: Type 1 coordination calls for a gL/gG fuse rated 63 A; Type 2 coordination calls for a gL/gG fuse rated 25 A. These are the fuse ratings that ensure the contactor survives a fault without welding or excessive damage, depending on your coordination philosophy.
The S0 frame measures 45 mm wide, 85 mm high, and 90 mm deep. Altitude derating applies above 2,000 m maximum operating altitude. The coil operates at 50/60 Hz with a rated control supply voltage of 220 V at 50 Hz and 220 V at 60 Hz — note it's a 220 V coil, not 24 V or 230 V, so verify your control voltage matches. Auxiliary contact ratings: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V. These are the switching capacities for the built-in auxiliary contacts — useful for interlocking or status feedback to a PLC input.