The reader of this guide will find discussions of ways to identify and improve voltage quality in power systems, as well as references to publications in this area. More specifically, this guide includes: a) Voltage quality levels from benchmarking studies b) Factors that affect power system performance c) Mitigation measures that improve power system performance d) References to current relevant in-depth IEEE standards and other documents.This guide only addresses subjects in depth where no other power quality reference does so. It is a"gateway" document for power quality that points the way to other documents in this field. The primary purpose in writing this guide is to assist power delivery system designers and operators in delivering power with voltage quality that is compatible with electrical end-use equipment. Another purpose is to point utility system customers toward power quality solutions that may exist in the power utilization system and equipment. Revision Standard - Superseded. The use of some electrical equipment attached to typical power systems creates voltage quality concerns. There is an increasing awareness that some equipment is not designed to withstand the surges, faults, distortion, and reclosing duty present on typical utility distribution systems. Traditional concerns about steady-state voltage levels and light flicker due to voltage fluctuation also remain. These concerns are addressed by this guide by documenting typical levels of these aspects of voltage quality and indicating how to improve them. Other documents that treat these subjects in more detail are referenced.