The ABB OMD300E480C‑A1 Control Unit is an accessory control module designed to work with ABB motorized change‑over switches (such as OTM40 … 2500 series) to assemble an automatic transfer switch (ATS) system. This unit provides the control interface that enables automatic switching between power sources (e.g., utility and backup generator) based on predefined conditions. The product includes the control unit itself, PCB connectors, and mounting hardware for panel or door installation.