A fundamental understanding of the operation, selection, and application of ac adjustable-speed drives on 2400 to 13 800 V auxiliary systems in electric power generation stations are provided in this guide. This guide applies to dc link type, ac adjustable-speed drives (ASDs) and does not address other drive systems such as cycloconverters. Included are overviews of ASD terminology, theory of operation, and a discussion of the factors that can influence equipment selection. Also defined are drive system classifications, design considerations, the interactions between the ASD and the electric supply system and the driven load, economic evaluation approaches, and typical applications. Finally, guidance on ASD specifications and installation are provided.