This guide addresses the application@ design concepts@ and implementation of computer-based control systems for hydroelectric plant automation. It addresses functional capabilities@ performance requirements@ interface requirements@ hardware considerations@ and operator training. It includes recommendations for system testing and acceptance. The electrical protective system (generator and step-up transformer) is beyond the scope of this guide. Purpose This guide is directed to the practicing engineer who has some familiarity with computer-based control systems and who is designing or implementing hydroelectric unit or plant control systems@ either in a new project or as a retrofit to an existing one. Although this guide is aimed primarily towards large hydroelectric power plants@ many of the concepts are applicable for small hydroelectric power plants (i.e. unit size 5 MVA or smaller). Further details on small hydroelectric power plant control concepts can be found in IEEE Std 1020? [B46].1@ 2 Typical hydroelectric system control logic upon on which this guide is based can be found in companion guide IEEE Std 1010? [B45] or IEC 61362 [B22].3 1 IEEE publications are available from the Institute of Electrical and Electronics Engineers@ 445 Hoes Lane@ Piscataway@ NJ 08854@ USA (http://standards.ieee.org/). 2 The number in square brackets refer to the references listed in the bibliography in Annex A. 3 IEC publications are available from the Sales Department of the International Electrotechnical Commission@ PO Box 131@ 3 rue de Varemb??@ CH-1211@ Gen??ve 20@ Switzerland/Suisse (http://www.iec.ch/). IEC publications are also available in the United States from the Sales Department@ American national Standards Institute@ 11 West 42nd Street@ 13th Floor@ New York@ NY 10036@ USA.