Request : What is the criteria in an application of power
   modules with regard to amount of motor starters and distribution of 
   potential?

Suggestion : A power mudule serves to supply load power to motor 
   starters.
   It is possible to configure load groups and potential groups. 
   A potential group always requires its own power module.
   One power module can be used for several load groups with a rated current of 
   max. 40 A each (at common potential)
   From the electrical point of view, up to 20 motor feeders can be allocated to
   one power modul.
   A total maximum physical length of 100 cm of an ET200S station is permitted.