What it is and what it does
The Siemens 3RT1025-1AN00-1AA0 is a SIRIUS power contactor in the S0 frame size, with three normally-open main contacts and screw-type terminals for the main circuit. It is designed for switching motor loads and other inductive loads in industrial control panels, mounting on a 35 mm DIN rail per EN 50022 via screw or snap-on fixing.
Key ratings and what they mean for fit
Rated for AC-3 duty at 400 V, this contactor switches 15.5 A — that is the motor-running current it handles under full load, not just the inrush. At 690 V it is rated 11 kW, and at 500 V, 10 kW, giving the buyer a clear kW-per-voltage map for motor sizing. The AC-2 rating at 400 V is 7.5 kW, for slip-ring motor applications where the load current stays higher during starting. The S0 frame (45 mm wide, 85 mm tall, 91 mm deep) fits standard panel layouts. Side-by-side mounting is permitted with a 6 mm gap to adjacent devices, so you can pack multiple contactors on the same DIN rail without derating — useful for grouping motor starters in a multi-pump or conveyor section. Operating temperature spans -25 to +60 °C, with a maximum altitude of 2,000 m. The pollution degree 3 rating means it is suited for industrial environments with conductive dust or humidity — typical for factory-floor panels not in a clean room.
Termination and wiring
Main circuit terminals accept 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), and up to 2x (0.75 to 4 mm²) solid or stranded wire. For the main current path, larger cross-sections are supported: 2x (1 to 2.5 mm²), 2x (2.5 to 6 mm²), and max 2x 10 mm². AWG equivalents for the main contacts are 2x (16 to 12), 2x (14 to 10), and 1x 8. The control circuit terminals handle 2x (0.5 to 1.5 mm²) and 2x (0.75 to 2.5 mm²).
Protection and coordination
For Type 2 coordination (limited damage under short circuit) the required fuse is gL/gG 25 A. For Type 1 coordination (device must be replaced after fault) the fuse can be up to 63 A gL/gG. This lets the panel designer balance protection level with fuse availability.