What this SIRIUS S0 power contactor is and where it fits
The Siemens 3RT1024-1AR10 is a SIRIUS power contactor in the Size S0 frame, meaning it occupies 45 mm width on a DIN rail (DIN EN 50022) and is intended for switching motor loads in control panels. It carries 3 normally-open main contacts and zero NC main contacts — a straight three-pole make configuration for three-phase loads. The AC-4 rating of 12.5 A at 400 V is the figure that governs plugging, inching, and reversing duty — the high-stress switching events that wear contacts fastest. For less demanding AC-2 duty (starting and running slip-ring motors), it is rated 5.5 kW at 400 V. Across the line, it handles 7.5 kW at both 500 V and 690 V, giving it reach into 690 V industrial networks without derating the power rating. Screw-type terminals on the main circuit accept conductors up to 2x 10 mm² (or 1x 8 AWG), and the auxiliary circuit accepts 2x (0.5 to 4 mm²). The front face carries IP20 protection — safe for finger-probe access inside a closed panel — while the terminal area is IP00, so it expects enclosure protection.
Mounting and integration into a panel
Mounts via screw or snap-on onto 35 mm standard rail per DIN EN 50022. Side-by-side mounting is permitted, so you can gang multiple S0 contactors without spacing — useful for compact motor starter assemblies. The 45 mm width per pole set is the standard S0 footprint; if you are swapping out an older S0 contactor, the 3RT1024-1AR10 drops into the same rail space. Depth of 91 mm and height of 85 mm mean it clears most standard enclosure depths. Allow at least 6 mm clearance at the side for airflow and wiring access. Operating temperature range of -25 to +60 °C covers most indoor panel environments; pollution degree 3 means it is rated for conductive pollution environments typical of industrial floors.
Coordination and protection
For Type 1 coordination (no damage to the contactor but it may need replacement after a short circuit), the maximum fuse is 63 A gL/gG. For Type 2 coordination (contactor remains usable after clearing the fault), the maximum fuse drops to 25 A gL/gG. This is the spec the panel designer needs to confirm the upstream protection device. Mechanical life is rated at 10 million operations — typical for this frame size in moderate-duty cycling. The auxiliary contact ratings cover common control voltages: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, and 0.3 A at 220 V DC.