The Siemens 3RT1026-1AN24 is a SIRIUS power contactor in size S0, rated for 11 kW at 400 V in AC-3 duty — the motor-switching rating that governs the real load it can handle. It carries 11 kW at 500 V and 690 V as well, so the same unit covers 400 V, 500 V, and 690 V motor circuits without up-sizing. Front face is IP20; the terminal area is IP00, meaning the wiring compartment is open to the panel environment — standard for contactors mounted inside a closed enclosure. Width is 45 mm, depth 140 mm, height 85 mm. Side-by-side mounting is allowed — no gap needed between contactors on the rail, which saves panel width.
Ratings and Coordination
AC-4 rating at 400 V is 15.5 A — that is the reversing or inching duty current, lower than the AC-3 motor rating. For frequent plugging or jogging, size the contactor against the AC-4 figure, not the AC-3 kW number. Type 2 coordination (no-weld after fault) requires a 35 A gL/gG fuse upstream. Type 1 coordination (equipment may be damaged but no fire risk) allows a 100 A gL/gG fuse. The 35 A fuse is the tighter protection that keeps the contactor reusable after a short circuit.
Main and auxiliary/control circuits use screw-type terminals. Main terminals accept 2x (1 to 2.5 mm²) solid or stranded, up to 2x 10 mm² maximum. Auxiliary/control terminals accept 2x (0.5 to 1.5 mm²) solid, 2x (0.75 to 2.5 mm²), or max 2x (0.75 to 4 mm²). AWG equivalents for main contacts: 2x (16 to 12), 2x (14 to 10), 1x 8. Two instantaneous auxiliary contacts are built in — no add-on block needed for basic signaling or interlocking.