GDF SUEZ Energie Nederland has been using OSIsoft’s PI System for about 15 years. This presentation will describe how the PI System is being used by the Generation and Power Dispatch groups in their daily processes. The PI System is used to monitor power plants, the PI Server itself and to perform calculations of plant performance using ‘data flows’ in PI ACE calculations and PI ProcessBook. It will also cover how data is sent to and received from other systems that are not ‘aware of the PI System’ through ‘loosely coupled’ connections and how PI System data and relational data are merged into the custom applications for end users. Finally a form of condition-based maintenance will be presented based on an automated maintenance signal using PI ACE calculations.