The Siemens SIRIUS 3RT1026-3AH00 is a Size S0 power contactor with three normally-open main contacts, rated for switching three-phase motor loads up to 11 kW at 400 V in AC-3 duty, and the same power rating at 500 V and 690 V.
The 11 kW AC-3 rating at 400 V is the headline motor-switching figure — it tells you this contactor handles a standard 15 hp (11 kW) four-pole induction motor on a 400 V line. For resistive loads (AC-1), the contactor is rated 10 A at 230 V and 6 A at 400 V. The AC-12 operating current is also 10 A, which covers control-circuit loads like PLC outputs or signal lamps. The AC-4 current of 15.5 A at 400 V is the figure to check if your application requires frequent plugging or inching — standard AC-3 switching doesn't stress the contacts the same way. The auxiliary contact ratings cover a wide control-voltage range: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V. That means the same auxiliary block works across 24 VDC and 110 VAC control circuits without swapping coils.
Dimensions are 45 mm wide, 85 mm high, 90 mm deep — a compact S0 footprint that fits standard 45 mm module spacing on the DIN rail. Main circuit terminals are screw-type, accepting 2x (0.25...2.5 mm²) solid or 2x (1...2.5 mm²) stranded, up to 2x 10 mm² or 1x AWG 8. The auxiliary terminals accept 2x (0.25...2.5 mm²) solid. Strip length is not stated in the spec, but standard practice for this terminal class is 8-10 mm. Short-circuit coordination: with type 2 coordination (no welding after fault), use a gL/gG fuse rated 35 A. With type 1 coordination (welding allowed but no fire risk), the fuse can go up to 100 A. The contactor itself has no instantaneous trip — it relies on upstream protection.
For BOM-freeze planning: the SIRIUS S0 platform is a mature, widely-installed family. If a second-source or drop-in alternative is needed, the closest functional peer is the 3RT1034-1AN60-1AA0 — but verify terminal layout and auxiliary contact configuration before substituting, as the frame size and mounting footprint differ.
The rated frequency is 50 Hz, with an operating range of 0.8 to 1.1 times nominal voltage at that frequency.