What it is and what it handles
The Siemens 3RT1025-1AK64-3MA0 is a SIRIUS power contactor in the S0 frame size, built for switching motor loads in industrial control panels. It mounts on a 35 mm DIN rail per EN 50022 — screw and snap-on — and uses screw-type terminals for the main current circuit. The contactor is rated for 7.5 kW at 400 V in AC-2 duty (slip-ring motor starting) and 15.5 A at 400 V in AC-4 duty (plugging/inching). At 690 V it handles 11 kW, and it carries a mechanical life of 10 million typical cycles.
What the ratings mean for fit
The AC-2 rating at 7.5 kW tells you this contactor is sized for slip-ring motor loads where the starting current is moderate — think crusher conveyors or mill drives that need controlled acceleration. The AC-4 rating at 15.5 A covers the severe inching and plugging duty that chews up a standard contactor quickly; this one is built to take that cycling. Pollution degree 3 means it's rated for the conductive dust and humidity you find in mining and processing environments — not a clean-room part. The operating range of -25 to +60 °C covers most pit and mill conditions without derating.
Mounting and integration
Snaps onto 35 mm DIN rail per EN 50022 — no tools needed for the rail mount, but the screw terminals need a screwdriver. The S0 frame is 45 mm wide and 85 mm tall, with a depth of 140 mm including terminals. Side-by-side mounting is allowed with 6 mm clearance to adjacent devices. The front face carries an IP20 rating (finger-safe), while the terminal area is IP00 so panel builders should guard live parts per local code.
Coordination and protection
For Type 2 coordination (no damage to the contactor on a short circuit) the spec calls for gL/gG fuses rated 25 A. For Type 1 coordination (contactor may need replacement after a fault) use 63 A gL/gG fuses. The solid and stranded wire ranges are given for both the main and auxiliary circuits — 2x (0.5 to 1.5 mm²) solid, 2x (0.75 to 2.5 mm²) solid, and up to 2x 4 mm² solid on the auxiliary side; the main circuit accepts 2x (1 to 2.5 mm²) single/multi-stranded, 2x (2.5 to 6 mm²), and max 2x 10 mm². AWG equivalents are also listed.