The fixed exhaust fan acts on the power cabin ventilation system. When the power cabin is ventilated and cooled, it is used as a mechanical exhaust fan. When fire smoke control, it can be used as smoke exhaust fan, which can effectively and timely discharge a large number of high-temperature smoke generated in the power cabin to the outside of the cabin and improve the cabin environment. The control box has a functional interface with the ventilation monitoring system of the power cabin, which is used to receive its remote control signal and upload equipment running status signal and fault alarm information to it.