The 3RA1943-2A is a SIRIUS wiring kit that provides the electrical and mechanical interconnection for a reversing starter built on a Size S3 contactor frame. It handles the cross-wiring between the forward and reverse contactors so the reversing starter functions as a single assembly. This part is in product phase-out. The preferred successor is the SIRIUS 3RA2 series order code 3RA2943-2AA1, which replaces the 3RA1943-2A in new builds and service replacements.
Phase-out reality and the successor path
The official successor is the 3RA2943-2AA1 from the SIRIUS 3RA2 family. For BOM lines still specifying the 3RA1943-2A, the 3RA2943-2AA1 is the drop-in replacement from Siemens. Verify the mounting footprint and wiring scheme against your panel layout before committing the change.
Poles and contactor frame size
The kit is designed for a 3-pole reversing starter configuration on a Size S3 contactor frame. The S3 frame is the medium-duty size in the SIRIUS contactor range, typically used for motors in the 15–30 kW range depending on duty cycle and voltage. It eliminates point-to-point wiring errors between the two contactors.