"转换开关装置" can be translated into English as "changeover switch device" or more commonly and concisely as "changeover switch" （if referring to the integrated equipment rather than emphasizing the "device" aspect separately）.
"Changeover switch" is widely used in electrical engineering contexts to refer to a switch that can transfer a circuit from one power source or circuit configuration to another.
If you specifically want to emphasize the "device" part, "changeover switch device" is also acceptable, though somewhat redundant in everyday technical usage.