Since the level of industrial automation increasing demands, on the one hand the amount of electric valve using more and more, on the other hand the electric valve control requirements have become more sophisticated and more complex. Therefore, the electric valve design electrical control are constantly updated. With the popularization and application of scientific and technological progress and the computer, the new, diverse electrical control will continue to appear. Consider the overall control of electric valves, electric valves should be selected control mode. For example, according to project needs, whether to use the centralized control or single control mode, if linked with other equipment, program-controlled computer program or application control, etc., the control principle is not the same. Valve actuators manufacturers sample given only standard electrical control principle, the use of electric equipment production sector should plant technical tests, a clear technical requirements. Here to introduce a classification under the electric valve electric valve. Electric valve consists of valve, valve seat, valve and other parts, dual seat, double-cone valve structure. Products are mainly used for steam piping, adjust the pressure. Widely used in cogeneration, textile, printing and dyeing, petrochemical, sugar refining and other industries. Advantages and disadvantages of electric valves: Valve is closed parts (gate) to move in the vertical direction of the channel axis of the valve, the pipeline is mainly used as a cutting medium, namely the use of fully open or fully closed. In general, the valve can not be used as a regulating traffic. It can be applied to low pressure can be applied to high temperature and pressure, according to the valve of different materials. But generally not used for pipeline transportation valve mud and other media. Electric Valve Advantages: ① fluid resistance; ② opening and closing the desired torque is small; ③ can be used in both the direction of flow of the medium to the ring road network, which means that the flow of media unrestricted; ④ When fully open, the sealing surface Erosion by the working medium is smaller than the cut-off valve; ⑤ physical structure is relatively simple, the manufacturing process is better; ⑥ relatively short length of the structure. Valve shortcomings: ① large dimensions and opening height, the space required for the installation also large; ② opening and closing process, the sealing surfaces were relatively friction, wear large, even at high temperatures likely to cause abrasions; ③ General valve has two sealing surface, to give processing, polishing and maintenance of some of the difficulties increased; ④ long opening and closing times. Source: http: //www.sddexin.com/ Siemens electric valve