Adjustable Speed Drive (ASD) Posted on 1st November 201514th July 2021 by ThePD (The Project Definition) Adjustable Speed Drive (ASD) refers to the Variable Speed Drive (VSD). 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 Engineering and tagged engineering, equipment, term. 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.