调压阀的作用是当机组甩负荷导叶快速关闭和同时调压阀相应快速开启，将机组关闭时减少的流量通过调压阀排出，待机组关闭后再缓慢关闭调压阀，也就是说，装设调压阀后，引水系统骨的流量变化得以缓慢进行，从而削减了水压上升值。另一方面，由于机组仍然是快速关闭的，从而保证了速率上升值也不会过高。

调压阀是降低长引水系统压力上升值和机组速率上升值的有效措施之一，在这方面起到了代替调压井的作用。

The pressure regulating valve is a safety device for the hydropower station of long pressure diversion tunnel;When the pressure diversion pipeline ∑ LV/H is greater than 15 to 30,a surge shaft needs to be set.Because the amount of civil works for a surge shaft is large,and the construction period is long,a pressure regulating valve is used to replace the surge shaft,thus saving investment and shortening the construction period.
The pressure regulating valve functions to discharge the flow reduced when the unit is shut off while the unit's rejection load guide vane is quickly closed and the pressure regulating valve is quickly open accordingly,and it will then be slowly turned off after the unit is shut off;that is to say,after a pressure regulating valve is installed,the water flow of the diversion system changes slowly,thus reducing a rise in water pressure.On the other hand,as the unit is still closed fast,it ensures that the rate will not rise too high.
The pressure regulating valve is one of the effective measures to reduce the rise in the pressure on the long diversion system and the rise in the rate of the unit,and it plays a role in replacing the surge shaft in this regard.