Reaffirmed March 2012. This guide is intended for the hydroelectric power industry to assist hydroelectric power plant owners, operators, and designers in the economic (feasibility) and technical evaluation (electrical aspects) of existing hydroelectric installations for rehabilitation. It addresses conventional hydropower. Portions of this guide are relevant to pumped storage but the unique features of pumped storage are not covered. Feasibility study results may indicate redevelopment of the site. Redevelopment will not be treated in detail in this guide. This guide covers all generating equipment up to and including the main transformer and typical auxiliary equipment.