Please advise us whether the fans installed at lift lobbies can perform the following functions. (Since there are two functions, the plural form is needed).
1. Centralized control for fans.
2. On signal keep on as suspending the power supply to fans (Is "kept" better?)
or Keep on a "on" signal in the fans as suspending the power supply (Is it better or not?)
Sorry, I am not sure about the intended meaning of second sentence? Is it a description of a problem with the fan?