Apr. 10, 2017
A surge tank is a small reservoir or tank in which the water level rises or falls to reduce the pressure swing at the turbine inlet which are transmitted in a fully closed circuit. In a summarized way the surge tank in hydro power plant serves the following purposes.
The main purpose to reduce the distance between surface and turbine thereby reducing the water hamming effect on penstock and also to protect the upstream tunnel from the high pressure rises.
Water hamming effect: it is defined as the change in pressure rapidly above or below normal pressure caused by sudden change in water flow through the pipe according to the turbine power demand.
It serves as a supply tank to the turbine when the water in the pipe is accelerating during increased load conditions and as a storage tank when the water is decelerating during load rejections or reduced load conditions.