What it is and where it fits
The Siemens 3RT1025-1AH24-1AA0 is a SIRIUS S0-frame power contactor with a 24 VDC coil, rated for motor switching in AC-2 duty at 7.5 kW / 400 V and AC-4 duty at 15.5 A / 400 V. It snaps onto a 35 mm DIN rail per EN 50022 — standard panel integration for motor control centers and distribution boards.
Motor duty and coordination
For AC-2 (slip-ring motor starting) the contactor handles 7.5 kW at 400 V; for AC-4 (plugging/inching) the rating is 15.5 A at the same voltage. Type 2 coordination requires a 25 A gL/gG fuse; Type 1 coordination allows up to 63 A gL/gG — the fuse choice governs whether the contactor survives a fault or just clears it.
Mounting and environment
Screw and snap-on mounting onto 35 mm DIN rail per EN 50022. IP20 on the front, IP00 at the terminals — keep live parts behind the panel door. Operating temperature range -25 to +60 °C, altitude up to 2 000 m, pollution degree 3.