Time In Service Posted on 23rd December 20154th May 2021 by ThePD (The Project Definition) Time In Service means the period of time from the completion of the equipment installation to the operation period. Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on LinkedIn (Opens in new window) Related Posted in Operation and tagged operation. ThePD (The Project Definition) ThePD has been developing the Preferred Project Definitions based on the actual project execution and operation experiences and knowledge with the Project Language, and sharing with you daily basis.