a one-line diagram or single-line diagram is a simplified notation for representing an electrical system. The one-line diagram is similar to a block diagram except that electrical elements such as switches, circuit breakers, transformers, and capacitors are shown by standardized schematic symbols.

One line diagram can used to show a high level view of conduit runs for a  plc control System.

Fully integrated view with multiple voltage level handling
Unlimited main Panel / distribution boards and graphical sub- panels
Integrated AC/DC , Grounding & earthing Systems
Multi level nesting of sub- systems
Interfaces for management of Switching devices
Charger/ Rectifier /UPS modelling