Revision Standard - Inactive-Reserved. This guide is intended to complement IEEE Std 125, providing application details and addressing the impact of plant and system features on hydroelectric unit governing performance. It provides guidance for the design and application of hydroelectric turbine governing systems. There is a heightened awareness within the electric utility industry of the importance in the effective application of governing systems for dynamic stability. The need exists to provide guidance in the effective governing system application for a better understanding among users.