S0 direct starter for 60 mm busbar systems
The Siemens 3RA2120-4BH26-0AP0 is a SIRIUS direct-on-line starter in the S0 feeder size, designed to snap onto 60 mm busbar systems — a common panel layout in North American and European MCC builds. It ships as a pre-assembled unit containing the contactor 3RT2026-2AP00 and the link module 3RA2921-2AA00, so you wire the main circuit and control loop without piecing together separate components.
Panel fit and terminal wiring
The unit occupies 45 mm width on the busbar, with a depth of 165 mm and height of 260 mm. Clearance requirements: 50 mm upward, 20 mm forward, 20 mm to the side, and 10 mm downward; zero backward clearance needed, so it sits flush against the backplane. Mounting position is vertical only. The S0 frame size is the same as the circuit-breaker it pairs with — if you're coordinating with a 3RV2 breaker, the busbar adapter and terminal shrouds share the same footprint.
Ambient limits and storage
Rated for operation from -20 °C to +60 °C with temperature compensation active across that range. Storage and transport tolerance spans -50 °C to +80 °C — wide enough for unheated warehouses or container shipping.