What this contactor is and what it does
The Siemens SIRIUS 3RT1026-1AG64 is a power contactor in the S0 frame size, designed for switching motor loads in industrial control panels. It's rated 11 kW at 400 V in AC-2 duty (slip-ring motors) and carries 15.5 A at 400 V in AC-4 duty (reversing or inching). For resistive loads, the AC-12 maximum operating current is 10 A. The coil is wound for 100 V at 50 Hz and 100–110 V at 60 Hz, with an operating voltage range of 0.8–1.1 times rated at 50 Hz and 0.85–1.1 at 60 Hz. That's a tight tolerance — if your control transformer sags under load, you'll want to confirm it stays above 80 V at 50 Hz. Two instantaneous contacts (NO/NC) are on board, and the contactor mounts via screw or snap-on onto a 35 mm DIN rail per EN 50022. Side-by-side mounting is allowed with 6 mm clearance at the side.
Where it fits in the panel
At 45 mm wide, 85 mm tall, and 140 mm deep, this S0 contactor fits a standard DIN-rail footprint. The main circuit uses screw-type terminals accepting solid conductors up to 2x 4 mm² and stranded up to 2x 10 mm² (or 1x 8 AWG). That's enough for the motor leads on an 11 kW load at 400 V. The front of the contactor carries an IP20 rating — safe for finger-probe access in an enclosure. The terminal area is IP00, meaning the live parts are exposed if the panel door is open; standard practice is to mount it inside a locked cabinet or behind a cover. Pollution degree 3 (conductive or dry non-conductive pollution) is assumed, which is typical for industrial control rooms. Operating temperature range is -25 to +60 °C, and maximum altitude is 2000 m without derating.
Coordination and protection
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 panel is safe), use gL/gG 100 A. This is the spec the panel builder needs to match to the motor starter. Mechanical endurance is typical 10 million switching cycles. That's a long life for a motor contactor in cyclic duty — the limiting factor will be electrical wear under AC-4 inching, not the mechanism.