SIRIUS S0 power contactor — what the ratings mean for fit
The Siemens 3RT1023-1BM45 is a SIRIUS-branded power contactor in the S0 frame size, designed for switching motor loads and resistive circuits in industrial control panels. Its AC-12 rating of 10 A covers control-circuit and resistive loads; the AC-3 motor ratings are 4.5 kW at 500 V and 5.5 kW at 690 V, so it handles standard 4-pole induction motors in that power band. For reversing or plugging duty (AC-4), the contactor is rated 8.5 A at 400 V — a figure that governs the real thermal stress in high-cycle applications, not the higher AC-3 number.
Mounting and panel integration
Mounts via screw or snap-on onto 35 mm standard mounting rail per DIN EN 50022. The S0 footprint is 45 mm wide, 85 mm tall, 150 mm deep — the depth matters when planning gland-plate clearance or enclosure depth. Side-by-side mounting is allowed, with a 6 mm air gap at the side for heat dissipation. Pollution degree 3 (conductive pollution typical in industrial panels) is accommodated, so no additional conformal coating is required in most cabinet environments.
Terminal data and wiring
Main current circuit uses screw-type terminals. Solid conductors: 2x (0.5–1.5 mm²), 2x (0.75–2.5 mm²), max 2x (0.75–4 mm²). Stranded: 2x (1–2.5 mm²), 2x (2.5–6 mm²), max 2x 10 mm². AWG equivalents for main contacts: 2x (16–12), 2x (14–10), 1x 8. The IP20 rating on the front protects against finger contact; the terminal area is IP00 — wire entry is open, so panel builders should account for that in the wiring scheme.
Coil and switching data
The magnet coil draws 5.4 W DC both for closing and holding — no inrush spike, so the control transformer or PLC output can be sized for a steady 5.4 W per contactor. Switching capacity across the coil's voltage range: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V, 6 A at 230 V, 3 A at 400 V. The rated value for the coil is 220 V. Mechanical life is typical 10 million operations. Operating temperature range is -25 to +60 °C, with a maximum operating altitude of 2 000 m.