What Is an Electric Solenoid Actuator?

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  • Written By: Paul Scott
  • Edited By: A. Joseph
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  • Last Modified Date: 28 November 2019
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An electric solenoid actuator is an electromagnetic device that is used to supply remote working movement in order to switch, move or otherwise activate a secondary mechanism. These devices typically are used where executing these actions manually is not practical or safe. Electric solenoid actuators are simple, reliable devices that have only one moving part. They generally consist of a static wire wound coil connected via a control circuit to a suitable electrical power supply and a spring-loaded, moving metal plunger attached to the secondary mechanism. When the coil is energized by an electric current, a powerful magnetic field is generated, which pulls the plunger toward it, providing the required actuation movement in the process.

The unavoidable need for remote actuation of devices is a reality in most mechanical, electrical and electronic engineering fields. Devices that need activation in small, inaccessible places, long distances from staffing concentrations or in hazardous environments require a remote source of actuation input initiated either by operator inputs or by an automated system. One of the most reliable, cost effective and simple of these remote devices is the electric solenoid actuator. Robust and lacking in complex, high-maintenance parts, these devices are capable of producing bi-directional linear actuation motion with a single moving part. In fact, they seldom have more than two distinct parts in total.


The average electric solenoid actuator consists of a static wire coil wound onto a hollow, non-conductive bobbin. This coil is connected to a suitably rated alternating current (AC) or direct current (DC) power supply circuit, including a control system that allows the solenoid to be powered on demand. A moving ferrous metal plunger is placed in close proximity to the coil, parallel to its hollow core. In most cases, the plunger features a helical spring placed around the its body, and the spring is compressed when it moves. The plunger is, in turn, connected via a linkage to the device that requires activation.

When the control circuit is activated and the electric solenoid actuator coil is energized, a strong magnetic field is generated around it. This magnetic force acts upon the plunger by pulling it rapidly toward the coil, compressing the spring as it does so and providing the first phase of the solenoid's bi-directional movement. This movement is the working agent which then — because of the plunger's attachment to the secondary device — provides the actuation force. When the control circuit is deactivated and power to the coil is cut, the compressed spring returns the plunger to its original, neutral position, thus supplying the second phase of movement. The electric solenoid actuator is then reset and ready for the next duty cycle.


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