Thanks for the replys, i have something to think on now.
The Elektronikon controls the following, if i am not mistaken;
The Y-D motorstarter relays, and the time in Y before switching over, how long time to run before opening the loading/unloading valve, how long time to run unloaded before a shutdown, load and unload "windows", etc. All values are programmable.
It monitors air element output temperature, dew point at the cooler, air pressure, oil temp, emergency stop, motorload/overload, automatic restart after power failure (if selected), and probably something i've forgotten.
It also count the running hours loaded and unloaded. And of course a service counter where you can reset for oil change, seperator change, filter change, etc..