The Siemens 3RT1326-1AP00 is a SIRIUS-brand power contactor in size S0, with four normally-open main contacts rated for AC-2 duty at 11 kW on a 400 V line. That AC-2 rating covers slip-ring motor starting — the contactor handles the higher inrush and longer arcing of wound-rotor motors, not just standard squirrel-cage loads. The 50 Hz coil pulls in at 0.8 to 1.1 times rated voltage, so it holds in on a weak supply but drops out cleanly below that band. Screw-type terminals on both main and auxiliary circuits, with wire ranges from 0.5 mm² up to 4 mm² solid or 10 mm² stranded on the main side. The front face carries IP20 protection; the terminal area is IP00, so the contactor expects enclosure protection downstream. Side-by-side mounting is allowed — no derating gap needed when you pack them on the rail. Ambient operating range of -25 to +60 °C, pollution degree 3 (conductive pollution typical of industrial panels). Mechanical life is 10 million cycles typical; auxiliary contact reliability is spec'd at one faulty switching per 100 million operations at 17 V, 1 mA — that's a dry-circuit rating, so it handles PLC-level signals without contact oxidation issues.
Mounting and Panel Fit
Fastens by screw or snaps onto 35 mm standard mounting rail per DIN EN 50022. Dimensions are 61 mm wide, 85 mm tall, 91 mm deep — that's the S0 footprint, so it drops into the same cutout as other S0 contactors in the SIRIUS family without re-drilling the subplate. The 4-pole main circuit with all NO contacts means this contactor is typically used for resistive or lightly inductive loads where you need four switched lines — three-phase plus neutral, or two independent two-pole circuits. No NC main contacts are present, so it's not a reversing or star-delta configuration out of the box.
Coordination and Protection
For type 2 coordination (no damage to the contactor on a short circuit), the required upstream fuse is gL/gG 35 A. For type 1 coordination (contactor may need replacement after a fault), the fuse can go up to 63 A. That gives the panel builder flexibility: if downstream protection is coordinated for selectivity, you can use the 35 A fuse and keep the contactor in service after a fault.