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What Are Electrical Relays?


Relays are a commonplace component within countless systems and applications, serving as an electrically operated switch. With the use of input terminal sets and operating contact terminals, a relay may be used for the management of a single control signal or multiple. With their control of signals and their operational characteristics, relays also may convert smaller electrical inputs into larger outputs, increasing their uses and abilities. Capable of being either a switch or an amplifier, electrical relays are paramount for the functionality of circuits within many types of electronic equipment.

For a more standard electromagnetic relay, the device may be composed of a solenoid wound with a coil of wire, an iron yoke with a low reluctance path, an adjustable iron armature, and various contact sets. The iron armature is mechanically attached to the contacts of the assembly, hinged on the yoke. A spring then serves to maintain the positioning of the armature when the component is de-energized, ensuring the presence of an air gap within the circuit.

When current is induced to the relays, the coil will become energized and will produce a magnetic field. This magnetism attracts the armature assembly, adjusting the positioning of the movable contacts to either make or break a connection. Upon the loss of power, the magnetic field will drop and the armature will return to its de-energized position with the aid of the spring so that contacts can readjust. While such methods are seen in more basic relay types, there are a number of variations that may feature different parts, components, and operations. Relays may also differ in their use of direct current or alternating current, each of which may affect certain aspects of operations.

The solid state relay is a more complex variation, coming in the form of an electric relay that is completely devoid of moving parts. Based on MOSFET technology, solid state relays will feature a single MOSFET or a paralleled array that feature substrate diodes that conduct current in the opposing direction of the assembly. Configured to be reverse biased, the substrate diodes will block any current when the relay is unpowered, switching to a biased positive state when the relay is actuated. Based on their design and method of operations, solid state relays are considered to be quicker and more reliable than electromechanical types, and are quite silent during activation.

As discussed previously, electrical relays can serve a variety of applications depending upon their design and configuration. When controlling high current loads, the electrical relay only requires a small amount of current to pass through the coil, allowing for the contacts to activate the larger load similarly to an actuator or switch. Electrical relays may also drive multiple outputs with a single input, managing several independent circuits. Lastly, relays also may be used to transmit varying forms of electrical signals, such as controlling an AC load with the use of a DC power source.

When choosing between electrical relays and solid state relay types, it is important to consider various factors to narrow down the best choice for a particular application. While electromechanical relays can be fairly affordable and reliable, the increased lifespan and rapid operations of a solid state relay may be beneficial for certain needs. Additionally, all relay components will have ratings for AC and DC current, all of which should never be exceeded for the safety of the component. Once you have decided upon a solution that is best fit for your particular needs, the experts at ASAP Semiconductor are readily available 24/7x365 to provide you personalized quotes for your comparisons and rapid lead-times on all that we carry. Give us a call or email today and see why customers choose to steadily rely on ASAP Semiconductor for all their part procurement requirements.


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