Main inlet valve is a device designed to control water flowing into turbine. The water shall flow into turbine by opening valve when machine put into operation, whereas when machine shut down, it will close valve to stop water flow into turbine. It shall be classified as: manual operated, electrical & manual operated, hydraulic controlled valve according to operation mode; and, butterfly valve, ball valve and gate valve as per types. Manual operated valve is applied for small turbine with low cost. Electrical and manual operated valve has low cost, easy controlling system, but its safety protection functioning is weak, the opening and closing time is long, and it is hard to operate when power plant in failure of power supply, moreover, electrical operated valve is not suitable for large valves. Hydraulic valve adopts micro-computer hydraulic control system, with safe, reliable, and strong functions, it could be opened and closed quickly. When the station power supply in failure, it could be operated through hydraulic control or counter weight system. The cost of hydraulic value is high, with complicated structure, difficult to maintain. General speaking, butterfly valve is applied for stations with water heads below 100m; gate valve is applied for those of middle & low water head, with diameter less than 800mm; ball valve is applied for those of high water head above 200m. Our company is able to supply various kinds of inlet valves as per clients requirements.