What it is and what it does
The Siemens 3RT1026-1AL00 is a SIRIUS power contactor in the Size S0 frame, with three normally-open main contacts and no normally-closed main contacts. It is rated for 11 kW motor switching at 400 V AC-3 and also 11 kW at 690 V AC-3, making it a direct-fit for three-phase induction motors up to that power in standard 400 V or 690 V line-fed panels. The contactor mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 50022, so it integrates into any standard enclosure without adapter plates.
Key ratings and what they mean for fit
The AC-4 rated current is 15.5 A at 400 V — this is the switching current for reversing or inching duty where the contactor makes and breaks motor current under full load. If your application cycles the contactor under load (crane drives, conveyor reversers), this is the number that governs contact life, not the AC-3 rating. The AC-2 rating at 400 V is also 11 kW, covering slip-ring motor starting. For resistive loads (AC-12), the contactor handles 10 A. The coil operates at 50 Hz with a voltage tolerance of 0.8 to 1.1 times rated. That means on a 230 V coil the contactor holds in down to about 184 V and picks up reliably at 253 V — useful if your panel has a weak supply or long cable runs. The auxiliary contact ratings span 10 A at 24 V down to 0.3 A at 220 V (–), so the same block can switch PLC-level DC loads or higher-voltage AC pilot circuits.
Mounting and wiring
Width is 45 mm, height 85 mm, depth 91 mm — the S0 footprint fits a standard 45 mm slot on the DIN rail. Side-by-side mounting is permitted without derating, so you can pack multiple contactors in a row. The main circuit uses screw-type terminals accepting 2x (1 to 2.5 mm²) solid/stranded, up to 2x 10 mm². The auxiliary circuit accepts 2x (0.5 to 1.5 mm²) up to 2x (0.75 to 4 mm²). No special tools beyond a screwdriver needed.
Protection and coordination
For Type 2 coordination (no damage to the contactor after a short circuit), the required upstream fuse is gL/gG 35 A. For Type 1 coordination (contactor may need replacement but the rest of the panel survives), a 100 A gL/gG fuse is allowed. The pollution degree is 3 (conductive pollution or dry non-conductive with condensation), which covers most industrial control panels. Maximum operating altitude is 2000 m without derating.