What Is Electromagnetic Relay - Types and Its Working Principle?

Electromagnetic relays are vital circuit elements in electrical and electronic applications. They play very vital roles in these systems. These devices operate via a coil that handles high-power circuits, and these are controlled through low-power signals via the contacts. Electromagnetic relays are crucial elements in today’s systems, and understanding the types and their working principle is vital for anyone in the electrical engineering field. This blog will go through the details of what is an electromagnetic relay, its types and its working.

What Is an Electromagnetic Relay?

An electromagnetic relay is a device that helps in manipulating an electrical circuit through electromagnetic means, even though it is operated electrically. Essentially, an electromagnetic relay has a wire coil, an electromagnetic armature, and at least one pair of electrical contacts. Upon passing an electric current through the coil, an electromagnetic field is produced, and this attracts the armature. This movement either makes or breaks the circuits by establishing or breaking the electrical contacts and hence either allowing or switching off the flow of current in the circuit.

Uses of Electromagnetic Relay

Electromagnetic relays are identified to be highly significant in a vast spectrum of uses within electrical and electronics related systems. These convenient tools are used to control and regulate electrical impulses in diverse situations. Here are some of the most common uses of electromagnetic relay.

• Control Circuits: Electromagnetic relays are employed in control circuits to perform the outputs of control contacts depending on the control inputs. For example, they can manage the amount of current received by a motor to start it or shut it down. This minute control is required in the industrial automation and process control industry.
• Protection Circuits: In the protection circuits, electromagnetic relays are used to protect the electrical equipment. They break the circulation of electricity during overcurrent or fault situations in an attempt to prevent damages or accidents. This protective function is important for enhanced credibility of electrical appliances and systems’ performance.
• Amplification: Electromagnetic relays can strengthen the signals electrically. This capability is especially relevant in radio and communication systems where interconnects shift between one or the other antenna or transmitter to ensure that the signal stability and quality are maintained.
• Timing: Such relays are also used in timing circuitries where it is needed to switch ON/OFF the circuits at predefined intervals of time. This functionality is applied to different applications like the switching off and on of streetlights and traffic signals and other timed electric controls.

Electromagnetic Relay Working Principle

The basic steps that can be taken when an electromagnetic relay is operated can be described as follows. First, before the relay is triggered, the contacts can be either in the normal state, the open state, or the closed state, depending on the relay. In the case of an electric motor, when a voltage is applied to the coil, it creates a magnetic field around the coil, and this pulls the armature towards it. This action alters the status of the contacts – if they were opened, these get closed; if closed, they get opened. 0n supply of voltage, a spring repositions the armature to release the sprung loaded contacts and return them to their initial position.

Types of Electromagnetic Relay

Different types of electromagnetic relays are available since they are used to perform discrete tasks within circuits. Broadly, these relays can be categorized into two main types: 

• Electromagnetic Induction Type Relay 
• Electromagnetic Attraction Type Relay

Electromagnetic Induction Relay

An electromagnetic induction relay is a protective relay that usually works through the induction process of an electromagnetic field. It is widely employed in alternative current power systems, particularly in power protection and control. There are three elements constituting this type of relay, namely the electromagnet, the moving conductor, which can be a disc or a rotor, and the contacts. The rotations are produced by flowing AC through the coil of the electromagnet. This field creates an electric current within a moving conductor, which in turn results in a rotary force that translates the conductor. The force overcomes the restraining force, and the conductor moves, making or breaking the relay contacts to cause a protective action such as a circuit breaker to isolate a faulty section. These relays, being popularly employed in electrical power systems, are suitable for overcurrent, directional, and differential protections. 

Electromagnetic Attraction Relay

An electromagnetic attraction relay is defined as a relay that works on the principles of electromagnetic attraction in order to manipulate circuits electrically. It is made up of an electromagnet, an armature, a spring, and a set of contacts. When electricity flows through the coil of the electromagnet there occurs the magnetic field that causes attraction of the armature. The action of the armature in turning shifts the location of the contacts, making or breaking a circuit. The relay goes back to the initial position when the current is cut off by the breaking system facilitated by the spring. Electromagnetic attraction relays are notable for many applications, such as switching, protection, and control applications in industrial & commercial power systems. These include predictable performance and high power load handling capability. These make the relays an important unit in electrical and electronic circuits.

Also Read: What Is Control Relays: Types, Functions And Applications

In the End

Electromagnetic relays are indispensable components in numerous electrical and electronic systems because they can use low-power signals to manage high-power circuits. These devices work on the foundation of electromagnetism and consist of a winding through which an electric current flows to create a magnetic field that attracts an armature, thereby making or breaking contacts. Electromagnetic relays can either be the traditional air-core, iron-core or the more advanced solid-state ones, reed or hybrid relays, and all these have their characteristics to suit the intended purpose. To achieve this goal, people who work in the field of electrical engineering need to comprehensively understand the operating principles and conditions of their application of each type of equipment.

Electromagnetic relay is used widely in industrial automation, telecommunications, automobile systems and home appliances due to its flexibility and steadiness. Getting into more details, it can be stated that the advancements in technology and achievements in creating new kinds of materials, increasing the density of the relay allows for expansion of the area of their application and increases the efficiency of this element.

In the case of high-end electromagnetic relays, Lauritz Knudsen Electrical & Automation is the one-stop shop for all your needs. Our products are built to very high-performance specifications to ensure the highest reliability under many forms of service applications.