抄録
The speed of a water turbine is regulated by a governor and a typical feed back control system is composed of the governor, the turbine and its load. The paper deals with the characteristics of a tachometric governor with temporary speed droop. First the dynamic properties of the governing system and the controlled system are expressed in the form of a block diagram, and a few considerations such as harmonic response, step response and self-excited oscillations of the system are conducted using an electronic analogue computer. Secondly, concerning the stability criteria of a surge tank system in a hydraulic power station, theoretical studies are pursued and compared with the classical Thoma formula which is based on the governing equation of ηQH=constant. The temporary speed droop equipped in the governor has an effective function to stabilize the surge tank system, and the paper presents a new formula which gives a smaller net area of the surge tank than that obtained from the Thoma formula.
