The Difference Between Relays and Solenoids

When procuring various electronic or electromechanical components, some may find themselves confused on the differences between relays and solenoids. While both are a form of switch that operate through the induction of electricity, both component types serve different applications due to their unique characteristics. As relays and solenoids are both common components found in a wide variety of industries and applications, understanding their differences can be very useful for making a well-informed purchasing decision.

At their most basic, a electromechanical relay is a type of electrically operated switch that contains a set of input terminals and a set of operating contact terminals. Relays can serve various needs, often used to control high-powered circuits with a low-power signal or for controlling several circuits with one signal. While solid-state relays that utilize semiconductor characteristics for their operations exist, most traditional relay types rely on an electromagnet that is induced with electricity to create a magnetic field powerful enough to open and close contacts. With the various types of relay components commonly available, such devices may serve for regulating signals, current, and voltages or for controlling the flow of power.

A solenoid in its most general form is an electromagnet, and they are implemented in various devices for the means of producing a magnetic field through a wound coil when electricity is induced. For types such as the solenoid switch, heavier currents ranging from 85 to 200 amps can be switched remotely. The solenoid switch type also features an enclosed plunger that is movable, and it may move in and out of the coil with the aid of a spring for its operations. While serving many applications, solenoids are commonly used for vehicle starters, electrical motors, winches, and other such components.

As relay and solenoid switch components both hold some similarities, there are various considerations one may make to narrow down the best choice for a particular application. When discussing the carrying capacity of both devices, the solenoid switch is more capable though tends to come at a more expensive price  Typically, the more carrying capacity a component has, the larger it will be. As such, one should always try and plan ahead on the design layout of the system and see whether a larger component can fit in an assembly if needed.

Similarly, one should also consider the environment that the switch will be placed in. Humidity, moisture, vibration, and dust can all have major effects on components, and devices will often denote what they have protection from or what they are vulnerable to. If there is extreme heat within the system due to standard operations, switches should be well protected or one should procure specific components that can withstand such high temperatures.

As a last major consideration, one should be aware of continuous and intermittent ratings, as well as the fact that solenoids are rated for both uses. Intermittent ratings mean that the component is capable of serving applications where there is a short activation period and a longer rest time. With continuous ratings, the component can operate with continual run time. While it may be possible for a continuous duty solenoid to act as an intermittent duty solenoid, an intermittent duty solenoid is incapable of providing for continuous demands.


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