Instability of a Hydraulic Turbine With a Very Long Penstock

Abstract

Hydraulic turbine instability at speed-no-load was experienced during the initial operation of two impulse turbines having very long penstocks. This paper describes the steps taken to achieve stability, including alteration of the mechanism between the governor and the needle servomotors. It is shown that while different governor dashpot settings may affect the operation of the governing mechanism, other changes in the mechanism external to the governor also profoundly affect the operation of the unit.