What this SIRIUS S0 contactor is and where it fits
The Siemens 3RT1026-1BG40 is a SIRIUS power contactor in the S0 frame size, designed for switching motor loads and resistive circuits in industrial control panels. It mounts on a 35 mm DIN rail per DIN EN 50022 via screw and snap-on fixing, occupying 45 mm of width — a standard slot in most panel layouts. The front face carries IP20 finger protection, while the terminals themselves are rated IP00, meaning the wiring zone is exposed and should be inside a closed enclosure.
Key ratings and what they mean for your load
The headline rating is 10 A at AC-12 (resistive load) — that is the maximum continuous current the main contacts can carry in a non-inductive circuit. For motor duty, the critical numbers are 11 kW at AC-2 (slip-ring motors, 400 V) and 15.5 A at AC-4 (plugging/reversing duty, 400 V). At AC-3 (squirrel-cage motors) the contactor handles 11 kW at both 500 V and 690 V, which covers common European and North American line voltages. These duty-specific ratings are the ones that govern real motor switching — the AC-12 figure alone would overstate capability on an inductive load.
Terminal wiring and coordination
Main current circuit terminals are screw-type, accepting solid conductors from 2x (0.5... 1.5 mm²) up to 2x (0.75... 4 mm²) for the smaller range, and stranded from 2x (1... 2.5 mm²) up to max 2x 10 mm². AWG equivalents are 2x (16... 12) and 2x (14... 10) with a single 8 AWG maximum. For Type 2 coordination (no weld) the required upstream fuse is gL/gG 35 A; for Type 1 coordination (welding allowed but no fire risk) it is 100 A. Pollution degree 3 (conductive pollution, typical in industrial enclosures) is the rated environment.
Coil and auxiliary contact characteristics
The DC magnet coil draws 5.4 W for both closing and holding — a single power figure, meaning the coil driver sees a constant load once energized. Auxiliary contact ratings cover DC switching: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V, and AC switching at 230 V (6 A) and 400 V (3 A). The contactor is rated for 10 million mechanical operations typical, and operates from -25 °C to +60 °C. Maximum altitude is 2,000 m without derating.