SIRIUS S0 power contactor — what the ratings mean for your panel
The Siemens 3RT1025-1BG44-1AA0 is a SIRIUS S0-frame power contactor with screw-type terminals, designed for screw and snap-on mounting onto 35 mm standard mounting rail per DIN EN 50022. Its 45 mm width and 85 mm height fit a standard DIN-rail footprint, with 150 mm depth leaving room for wiring ducts in a 200 mm deep enclosure. Rated 11 kW at 690 V AC-3 (the standard motor-switching duty class), this contactor handles three-phase induction motors up to that load. At 500 V it carries 10 kW, and at 400 V in AC-2 duty (slip-ring motors or resistive-inductive mixed loads) it manages 7.5 kW. For high-inrush reversing or plugging duty (AC-4), the rating is 15.5 A at 400 V — a lower figure that governs frequent jogging or inching applications. The DC coil draws 5.4 W on pickup and holds at the same 5.4 W — a continuous-duty solenoid that stays cool in a sealed panel. Operating temperature spans -25 to +60 °C, with pollution degree 3 (conductive pollution typical in industrial enclosures). The IP20 front face protects against finger contact; the terminal area is rated IP00, meaning the wiring compartment expects enclosure protection from the panel.
Coordination and wiring — what the protection specs tell you
Type 2 coordination (no damage to the contactor under short circuit) requires a gL/gG fuse rated 25 A upstream. Type 1 coordination (contactor may need replacement after fault) allows a 63 A gL/gG fuse. For a motor branch circuit, the 25 A fuse is the safer choice — it limits let-through energy and keeps the contactor in service after a fault. Main circuit terminals accept 2x (0.5 to 1.5 mm²) solid, 2x (0.75 to 2.5 mm²) stranded, or up to 2x 4 mm² max. For AWG, that's 2x (16 to 12) solid, 2x (14 to 10) stranded, or 1x 8 AWG. The auxiliary contact block (2 instantaneous contacts) shares the same terminal range. Side-by-side mounting is permitted with 6 mm spacing — no derating required for adjacent units at rated load.