Dehdashti - Pacific Gas and Electric Company San Francisco, California U.S.A.

The purpose of this paper is to present an overview of Voltage Instability and Voltage Collapse that have been reported worldwide in recent years and familiarize electric utilities with this consideration on their systems. The basic physics of the phenomenon is discussed, system planning and d operating cons iderat ions are. presented, and a few basic analysis techniques are also discussed. In addition, particular characteristics of a utility grid that makes it susceptible to Voltage Instability is presented.