The ABB OTM100F4C20D380C is a 4‑pole motorized automatic transfer switch (ATS) / change‑over switch designed to automatically and manually transfer electrical loads between two independent AC power sources — typically the utility mains and a backup generator — in three‑phase low‑voltage power distribution systems. This compact, robust device incorporates a motorized operator for automatic switching based on control logic and also supports manual override via a handle for maintenance or emergency operation. A mechanical interlock ensures that both power sources can never be connected at the same time, protecting equipment and enhancing safety during source transitions. The model’s “20D” designation indicates integrated control logic suitable for standard automatic transfer applications without needing a separate external controller.