SIRIUS S0 power contactor — 24 V DC coil, screw terminals
The Siemens 3RT1024-1HB40 is a SIRIUS S0-frame power contactor with a 24 V DC magnet coil drawing 4.2 W for both pick-up and hold. It mounts on a 35 mm DIN rail per EN 50022 via screw and snap-on, or directly with screws. The 45 mm wide body fits standard panel layouts; depth is 101 mm. Rated for motor duty: 5.5 kW at 400 V in AC-2 (slip-ring motor start/run) and 12.5 A in AC-4 (plugging/inching). The coil operates reliably from 0.7 to 1.25 times rated voltage — so at 24 V nominal, pick-up is guaranteed down to about 16.8 V and it holds through transients up to 30 V. Ambient temperature range is -25 to +60 °C during operation, with pollution degree 3 (conductive pollution typical in industrial panels). Side-by-side mounting is permitted without derating — the 6 mm side clearance is the minimum for heat dissipation when ganged.
Coordination and wiring
For type 2 coordination (no weld-stick after a short circuit), the required upstream fuse is gL/gG 25 A. For type 1 coordination (device may be damaged but no fire risk), use gL/gG 63 A. Main circuit terminals accept solid/stranded wire: 2x (1–2.5 mm²), 2x (2.5–6 mm²), or max 2x 10 mm². The auxiliary/control circuit terminals take 2x (0.5–1.5 mm²) or 2x (0.75–2.5 mm²), max 2x 4 mm². Rated operational current in AC-12 (control circuit duty) is 10 A maximum. The contactor's mechanical life is typically 10 million operations.