What it is and what it does
The Siemens SIRIUS 3RT1026-3BM40 is a power contactor in the S0 frame size, designed for switching motor loads in control panels. It mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 50022, taking up 45 mm of panel width. Rated for 11 kW at 400 V in AC-2 duty, it handles slip-ring motor reversing and plugging applications. In AC-4 duty (inching, reversing under load), it switches 15.5 A at 400 V. The AC-12 rating of 10 A covers resistive loads. The magnet coil draws 5.4 W for both closing and holding, a constant-power design that simplifies the control transformer sizing. Operating temperature spans -25 to +60 °C, with pollution degree 3 rated for industrial environments.
Mounting and wiring
The S0 frame is a compact, panel-friendly footprint — 45 mm wide, 85 mm tall, 100 mm deep. Side-by-side mounting is allowed, so you can gang multiple contactors without extra spacing, though the 6 mm side clearance to adjacent components or enclosure walls must be respected. Main circuit terminals are screw-type, accepting 2x (1 to 2.5 mm²) solid/stranded, 2x (2.5 to 6 mm²), or up to 2x 10 mm². AWG equivalents: 2x (16 to 12), 2x (14 to 10), or 1x 8. The auxiliary contact terminals accept 2x (0.25 to 2.5 mm²). For Type 1 coordination (no damage under short circuit), use a gL/gG fuse rated 100 A. For Type 2 coordination (limited damage, device remains usable), the fuse drops to 35 A.
Lifecycle and sourcing
The reference code per DIN EN 81346-2 is Q (power switching device), which aligns with standard panel labeling schemas.