A Brief Description Of Electric And Electromechanical Actuators-winpm

Sales Actuator is a device used to control or generate motion. Depending on the how the power is generated for producing the motion, actuators can be broadly classified into electric, hydraulic, pneumatic, mechanical and electro-mechanical actuators. While hydraulic, pneumatic and mechanical actuators are used where more force is to be delivered, electric and electro-mechanical actuators are used in cases where better control is required. Better control in electric actuators is provided by the direct interfacing of the electric motor with the control unit. Electric actuators are available in both AC and DC power supply for voltage ranging from 24 volts to 230 volts. Mostly there are two types of electric actuators: Valve Motor Drive or VMD actuators and Modulating actuators. VMD actuators have three states- opening the valve, closing the valve and no movement. Their forward or reverse rotation is directly controlled by an external 3-position or two 2-position switch unit. These generally employ butterfly valves and hence are also known as electric butterfly valve actuators. Their valves are opened or closed with the help of valve positioners. The drawback with such actuators is that they cannot be used for a longer duration of time, and usually employ some limiting devices to prevent over-travel damage. Modulating electric actuators are used to position the control valve according to the requirement of the system. Usually such actuators use high rated motors of around 1200 starts per hour. Often they have a positioning circuit integrated within them, which accepts analog signals ranging from 0 to 10 Volts, or 4 to 20 mA. This control signal is then interpreted by actuator and accordingly valve is positioned between the limit switches. For precise positioning, the actuator is equipped with a potentiometer to function as a position sensor and sense the position of the valve. Potentiometer then updates the actual valve position to the positioning circuit, so that positioning circuit can position the valve accurately. Electro-mechanical actuators are a .bination of electrical and mechanical actuators. They are similar to the mechanical actuators with the only difference that electric motor is used instead of control knob or handle. Such actuators use 3 port solenoid valves , whose motion can be controlled by an electric supply. Such valves consist of parts like solenoid coil, electric connector, bon. nut, seal cartridge, O-rings, end connector, body and union nut. Electro-mechanical actuators convert rotary motion of the motor into linear straight line motion. The major disadvantage with such actuators is that they consist of several moving parts running each other, which makes them prone to wear and tear. About the Author: 相关的主题文章: