What It Is and Where It Fits
The 3RT1026-3KF40: This contactor mounts on a 35 mm DIN rail per EN 50022 — screw or snap-on — and fits a 45 mm wide slot. The S0 frame is the compact workhorse in the SIRIUS line, common in control panels for conveyors, pumps, and fans. Ambient range of -25 to +60 °C covers most indoor panel environments, and pollution degree 3 means it handles conductive dust and occasional condensation found in industrial settings.
Key Ratings and What They Mean for Your Panel
The AC-2 rating of 11 kW at 400 V is the one that matters for wound-rotor motors or slip-ring applications — that's the duty cycle where the contactor makes and breaks under load. The AC-4 rating of 15.5 A at 400 V covers plugging and inching, where the contacts take the full motor starting current each time. For resistive loads (AC-12), it's rated 10 A maximum. The main current circuit uses screw-type terminals accepting 2x (0.25...2.5 mm²) solid or 2x (1...2.5 mm²) stranded, with a max of 2x 10 mm². The auxiliary and control circuit uses spring-loaded terminals — no screwdriver needed for the coil and aux wiring, which speeds up panel wiring. The coil draws 4.2 W DC both on pull-in and hold, so there's no inrush spike to worry about on your 110 V DC supply. Type 2 coordination requires a 35 A gL/gG fuse; Type 1 coordination needs a 100 A gL/gG fuse. That's the selectivity headroom you need to design into your branch circuit protection. The IP20 front keeps fingers out; the IP00 terminal area means it's not touch-safe once wired — standard for panel-mount contactors.