I am looking for an ability to control the power inside a factory.
Example: I want disconnect a beacon if it is unused

Won't happen, sorry. You can disconnect the entire factory building though.

maybe it is possible to choose between:
- usual behaviour, all inside building is supplied, everywhere
- same as outside of building. You have to place the poles and connect them manualy to the big trafo inside the building

You could make this via switch, something like the existing power in / power out switch.

MagmaMcFry wrote:

Won't happen, sorry. You can disconnect the entire factory building though.

sry, but in this stage it works only outside. inside, recursion, there is no way for that.

I'd use recursion as seldom as possible anyway because it causes a lot of confusion

If you don't mind doing it manually, switching from input to output mode on power will depower the whole factory without using a power-switch, and at any particular level of recursion.
Of course, that's probably not what you're looking for, but I've used it when I've suddenly had a power drop and need to get my mines back up and running quickly.