What it is and what it does
The Siemens 3RT1026-1AL24-3MA0 is a SIRIUS power contactor in size S0, designed for switching motor loads in industrial control panels. Rated for 11 kW at 500 V in AC-3 duty, it handles the inductive load of standard three-phase induction motors up to that power level. For high-inrush applications like reversing or plugging (AC-4), it carries 15.5 A at 400 V — the rating that governs contactor life under severe switching duty. The AC-2 rating at 400 V is 11 kW, covering slip-ring motor applications where the load current stays closer to the starting value.
Mounting and panel integration
Mounts via screw or snap-on onto 35 mm DIN rail per EN 50022, which is the standard in most European-style control panels. The S0 footprint is 45 mm wide by 85 mm tall by 140 mm deep — a common size that fits alongside other SIRIUS components on the same rail. Side-by-side mounting is permitted without derating for ambient temperatures up to 60 °C, which simplifies panel layout for multi-contactor groups.
Wiring and terminal details
Main current circuit uses screw-type terminals accepting 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or up to 2x 4 mm² solid — or AWG equivalents 2x (16 to 12), 2x (14 to 10), or 1x 8. For type 2 coordination (no-weld after short circuit), the required upstream fuse is gL/gG 35 A. For type 1 coordination (welding allowed), use gL/gG 100 A.