The Siemens 3RT2023-1BG40 is a SIRIUS power contactor in Size S0, designed for switching motor loads and resistive circuits in industrial control panels. It carries a 24 VDC coil with screw-type terminals and mounts onto 35 mm DIN rail per DIN EN 60715, which means it integrates directly into a standard panel layout without adapters.
What the ratings mean for fit
The mechanical switching frequency hits 1 000 operations per hour under AC-1, AC-2, AC-3, and AC-3e duty, and 300 ops/h under AC-4. That 1 000 ops/h in AC-3 (motor starting) is the figure that governs conveyor or pump cycling — if your application needs faster cycling, this contactor will not sustain it. DC switching capacity is derated by voltage: 10 A at 24 V, 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, and 0.3 A at 220 V. For a 125 VDC solenoid or brake circuit, the 0.9 A limit is the one that decides fit — not the AC rating. The coil operates across -25 to +60 °C ambient, with storage range from -55 to +80 °C. That -25 °C floor means it is not rated for freezer or arctic outdoor installation without a heated enclosure. Wire range accepts solid or stranded 1 to 10 mm² on the main contacts, and 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) on auxiliary contacts. That covers standard motor leads up to about 4 mm² for a 4 kW motor; larger loads need a bigger contactor frame.
Mounting and integration
Fastened by screw and snap-on onto 35 mm DIN rail per DIN EN 60715. The mounting position allows +/-180° rotation on a vertical surface and +/-22.5° tilt forward/backward, so it fits in tight enclosures or angled subpanels without derating. Dimensions: 85 mm high, 45 mm wide, 107 mm deep. The 45 mm width matches the S0 frame standard — three units fit in a 135 mm wide DIN section. Clearance: 10 mm upwards, 10 mm forwards, 10 mm downwards, 6 mm at the side. That 6 mm side gap is tighter than the vertical ones; plan terminal access accordingly.