Electric actuators are devices that produce linear motion through the conversion of electrical energy into mechanical energy. This type of linear actuator is typically attached to valves that move as a result of an outside power source. The necessary power level is achieved through the use of single-phase or three-phase AC or DC motors and various gears.
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Electric actuators are divided into two different types: rotary and linear. When selecting an electric rotary actuator, important factors to consider include actuator torque and range of motion. Important factors to consider when selecting linear electric actuators include the number of turns, actuating force, and the length of the valve stem stroke. Both rotary and linear electric actuators are often used in a variety of applications and industries such as: automotive, for use in power door lock systems and air conditioning systems; industrial manufacturing, to be utilized as control components in many industrial devices; agriculture, for use in farming machinery such as combine harvesters and fertilizer spreaders; and power generation, in which they are particularly utilized for green technologies such as wind turbine construction.
The basic construction of an electric actuator consists of an electric motor, a screw, a nut and possibly gears if the electric motor is a small motor. In an electric actuator, it is the nut that provides the translation from electrical motion to mechanical motion when it rotates along the screw, moving forward instead of rotating along with the screw. Rotary electric actuators rotate from open to close using butterfly, ball, and plug valves. With the use of rotary electric actuators, the electromagnetic power from the motor causes the components to rotate, allowing for numerous stops during each stroke. Either a circular shaft or a table can be used as the rotational element. The actuator torque refers to the power that causes the rotation, while the full range of motion can be either nominal, quarter-turn, or multi-turn. Linear electric actuators, in contrast, open and close using pinch, globe, diaphragm, gate, or angle valves. Linear electric actuators are often used when tight tolerances are required. These electric actuators use an ACME screw assembly or motor-driven ball screw to supply linear motion. Within linear electric actuators, the load is connected to the end of a screw that is belt or gear driven.
