What this SIRIUS direct starter delivers
The Siemens 3RA2120-1JA24-0AP0 is a SIRIUS direct on-line starter in the S0 size — a pre-assembled combination of a contactor and overload relay, ready to bolt into a motor branch circuit. It ships with the 3RT2024-1AP00 contactor and the 3RA2921-1AA00 link module, so you're not sourcing those separately. Rated 10 A at 480 V (AC-3 duty), this starter handles a 7.5 hp motor at 460/480 V and a 10 hp motor at 575/600 V. The Trip Class 10 protection means it trips within 10 seconds at 600% of the set current — standard for general-purpose motor starting like pumps, fans, and conveyors. The insulation voltage is rated 690 V, giving headroom on 400/480/600 V systems without derating the main circuit.
Mounting and panel fit
Mounts via screw fixing or snaps onto 35 mm DIN rail — the dual-method gives panel builders flexibility. The mounting position is vertical only, so plan the DIN rail orientation accordingly. Dimensions: 193 mm height, 45 mm width, 97 mm depth. The S0 footprint is compact for a 10 A starter, but the 193 mm height means it won't fit shallow enclosures — check your backplate clearance. Clearance requirements: 50 mm above, 20 mm below, 20 mm to the side, 10 mm downward, and 0 mm backward from the mounting surface. The upstream circuit-breaker must be S00 frame size to match the feeder.
Environmental and compliance
Operating temperature range -20 to +60 °C, storage and transport -50 to +80 °C. The temperature compensation is active across the full operating range, so the overload trip curve stays accurate.