What Is a DC Actuator?

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  • Written By: Ray Hawk
  • Edited By: E. E. Hubbard
  • Last Modified Date: 29 April 2020
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A DC actuator is an electro-mechanical switch powered by direct current (DC). While actuators come in many sizes, usually large-scale versions are run off of alternating current (AC) as they must handle heavy mechanical loads. The DC actuator tends to be found in small electronic devices like doorbells or systems where the movement of a millimeter- or centimeter-sized shaft or screw assembly is used to activate a circuit or change the orientation of a mechanical device. In this sense, they are often part of a microcontroller system on an assembly line or in other self-contained machinery such as the valves and throttle control linkage in automobiles. The DC actuator often acts in concert with an integrated circuit chip to regulate the flow of gasses or liquids, or to switch mechanical systems on and off in pipelines and other industrial applications.

The most common type of DC actuator system is the linear actuator. This is a device that generally converts rotational motion to linear motion through electrical power, and can operate assembly line hatches and chutes, align solar panels toward the sun, and perform other forms of automation. The DC actuator system generally has little torque or linear force, however, and is often powered by 12- or 24-volt DC batteries that are meant to only handle intermittent loads. Types of actuators in the DC range are usually classified as linear if they can move more than one pound (0.45 kilograms) and as micro actuators if they can move less than one pound.

One of the advantages of a small-scale electronic DC actuator over that of a heavy-duty AC actuator that runs on pneumatic or hydraulic power is that the smaller units can often serve the dual role of acting as potentiometers. That is, the movement of the shaft in the actuator can be precisely controlled and measured by regulating the electrical force that is applied to the system. This can make them very useful units in gear drives that have very fine tolerances, such as in robotics systems.

In some cases, DC actuator parts can greatly resemble those of small electrical motors. This is the case with what is known as stepper motors, which are both an electrical motor and a DC actuator at the same time. A stepper motor is a small DC motor connected to a microcontroller circuit, where the rotational distance of the motor shaft is precisely incremented in small fractions of a total rotation of the shaft. While an ordinary DC motor usually spins at dozens or hundreds of revolutions per second, a stepper motor can be set to only rotate 1.8, 3.6, or 7.5 degrees out of a total 360 degrees for one complete rotation. Such precise control is necessary in micro-robotics systems such as for moving the aerilons on radio-controlled aircraft used both in military and recreational arenas.


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