SIRIUS S0 power contactor — 11 kW at 690 V, screw terminals
The Siemens SIRIUS 3RT1025-1BE44-1AA0 is a Size S0 power contactor rated for motor switching up to 11 kW at 690 V AC-3 and 10 kW at 500 V AC-3 — the AC-3 figure governs the real motor load, not the AC-1 resistive rating. In AC-4 reversing or plugging duty it handles 15.5 A at 400 V, so it suits frequent inching or jogging applications where the contactor sees high electrical wear. The coil draws 5.4 W DC for both closing and holding, which means the control transformer can be sized for a steady load — no inrush spike beyond the sealed power. Side-by-side mounting is permitted — no gap needed between contactors — which simplifies panel layout when stacking multiple units for multi-motor groups.
Main current circuit uses screw-type terminals accepting 2x (1–2.5 mm²) solid, 2x (2.5–6 mm²) stranded, or max 2x 10 mm² — enough for the rated motor currents without piggyback lugs. The auxiliary contact terminal accepts 2x (0.5–1.5 mm²) solid, 2x (0.75–2.5 mm²) stranded, max 2x 4 mm². AWG equivalents for the main contacts are 2x (16–12), 2x (14–10), 1x 8.
This lets the panel designer choose between tighter protection or higher fault-clearing capacity depending on the motor branch.