Siemens SIRIUS 3RT1024-3AL28-1MA2 — Power Contactor, S0 Frame
Rated for AC-2 duty at 400 V at 5.5 kW and AC-4 at 400 V at 12.5 A, this contactor handles reversing or plugging applications where the motor sees frequent starts and stops — AC-4 is the tougher duty cycle, so that 12.5 A figure is the one to watch for high-cycle loads like conveyors or hoists.
Main circuit terminals are screw-type, accepting 2x (1…2.5 mm²) solid or stranded, 2x (2.5…6 mm²), or up to 2x 10 mm². AWG equivalents: 2x (16…12), 2x (14…10), or 1x 8. The front has IP20 finger-safe protection; the terminal area itself is IP00, so panel builders should guard against accidental contact inside the enclosure. Depth of 140 mm means it fits most standard 200 mm deep enclosures, but check gland-plate clearance if the panel is shallow or has a rear-mounted busbar system.
Type 1 coordination (contactor may need replacement after fault) allows a 63 A gL/gG fuse. This matters for selectivity studies — if the panel demands Type 2, the 25 A limit governs the branch circuit design. Degree of pollution 3 means the contactor is rated for conductive pollution environments typical of industrial control panels — no special conformal coating needed for normal factory air.