What is a relay, its functions, types and connection diagram of a relay

A relay is an electrical component that can control the flow electricity in the circuit. The relay can be on at one time and de-energized at another. This allows the relay to open and close, as well as interrupt and restore electrical circuits.

This blog post shows you the most important things you need to know about the relay. So if you're curious about relays, keep reading!

What is a relay used for?

relay can be use in many types of products. For example, a car's starter has several relays that control things like the fuel pump and ignition coils.

They are also very general in household appliances such as a toaster or refrigerator.

In fact, most modern household appliances have a bunch of relay. However, in many different types of devices and systems, one relay is not enough to achieve the end goal. Then power relays come into play.

How does a relay work?

For a relay to work, it needs three main components: coil of wireTo switch which can open the circuit, and set contacts.

When the relay is not in use, current flows through coil of wire and then back to the battery. The key element of the relay is the switch, which can interrupt this flow of electricity. It does this by opening some contacts that break the circuit.

In turn, when these contacts are open, it prevents current from flowing. flowing on a coil Sveta. In addition to this function, there are other types of relays that have many different functions such as temperature control or shock protection for sensitive equipment.

We hope you now understand what a relay is.

Normally open and normally closed relays

Normally open relays are switches open by default. This means that electrical current will flow through the switch when it is in the open position.

Normally closed relays, on the other hand, are switches that closed by default. This means that no electrical current will flow through the switch when it is in the open position.

How to connect a relay?

When connecting a relay, it is important to remember that the relay must be controlled by switch which can handle the current that the relay will draw. Also, you must have a way to ground the relay.

The easiest way to do this is to connect land wire from the relay to the ground screw on the chassis.

Finally, you must make sure that the voltage rating of the relay is large greater than or equal to the rated voltage of the circuit.

Learn more about how relays can be used.

Relay types

1. Electromagnetic relays
2. Blocking relays
3. Electronic relays
4. Momentary relay
5. Reed relays
6. High voltage relays
7. Small Signal Relay
8. Time delay relay
9. Multidimensional relays
10. Thermal relays
11. Differential relays
12. Remote relays
13. Automotive relays
14. Frequency relay
15. Polarized Relays
16. Rotary relays
17. Sequence relay
18. Moving coil relay
19. Buchholz relay
20. Safety relay
21. Control relay
22. Earth fault relay

Electromagnetic relays

Electromagnetic relays are used in various applications. They are often found in household appliances such as refrigerators, microwave ovens, and toasters. In these cases, usually one relay controls many instrument functions. I

In other types of products, such as vehicles or industrial machines, multiple relays work together to achieve a goal. Electromagnetic relays are a very common type of relay used in a wide variety of products.

Blocking relays

In a latching relay, the switch for controlling the circuit is located inside the relay. When the relay is not in use, it is closed and electricity flows through the coil of wire and then back to the battery, which completes the circuit.

However, when a relay is used to break a circuit, it opens some of the contacts that break that circuit. As mentioned earlier, these contacts are controlled by a switch that is inside the relay.

For a blocking relay to work properly, there must be a way for its current to function in both directions. This allows you to open and close it as needed.

Electronic relays

The electronic relay can be seen as an update to traditional electromagnetic relays. The advantage of an electronic relay is that it can be controlled by a remote signal, which means that only one switch needs to be inside the instrument. This allows any external controls to control the device no matter where it is located.

Although they are more expensive than traditional relays, they are much easier to wire and make testing much easier. This is because it requires only one switch to be used instead of two or more, which can make it difficult to connect to certain devices.

Momentary relay

Momentary relays are very similar to latching relays in that they both require a coil of wire, a circuit switch, and contacts to open the circuit. However, the contacts do not remain open, but close as soon as the power goes out.

These types of relays are often used in applications where it is necessary to complete a circuit and then remove it immediately after the task is completed. This is why these relays are often used in car alarms and car remotes so that they can work even without batteries because there is no need to maintain an open circuit.

Reed relays

A reed relay is similar to an electromagnetic relay in that it has a coil, contacts, and a magnet that act as a switch to open or close a circuit.

However, instead of this magnet being located in the center of the device, as in traditional relays, it is located at one end of it. To complete the circuit, you simply need to connect the two ends of the reed switch, which causes the magnet to touch and complete the circuit. This works similarly to a switch in that as soon as contact is lost, current flows and therefore completes the circuit.

High voltage relays

A high voltage relay is a type of relay capable of withstanding higher voltages.

Typically, this type of relay has extra insulation throughout the device to help protect it from unexpected shocks. This also means that these relays are only suitable for use in high voltage circuits. Be sure to look for the high voltage rating on the product before purchasing a relay.

Small Signal Relay

Small signal relays are often used in the medical industry to control voltage flow. These relay switches are capable of handling much lower voltages than high voltage relays, making them safer for use in sensitive equipment.

The only downside is that these small signal relay switches are quite large and bulky, so they cannot be used in compact small devices like mobile phones.

Time delay relay

Time delay relays are similar to on/off delay switches in that they use a small amount of current to hold the circuit open for a short period of time.

This makes them ideal for applications where the instrument must be turned off at night or at other times when it is not needed.

Multidimensional relays

A multidimensional relay is a type of relay that has 3 or more contacts and can therefore perform a range of functions.

This type of relay has the advantage that only one switch is required to operate multiple functions, saving space and wiring. This also means that parts are often cheaper than traditional relays.

Thermal relays

Thermal relays are known to be self-regulating and therefore do not require an external power supply. This design offers an inexpensive and reliable method that can be used in industrial or commercial applications.

The only drawback is that thermal relays are bulky and therefore not suitable for use in small circuits.

Differential relays

Differential relays are an interesting type of relay that has two contacts on one side for high voltage circuits and two contacts on the opposite side for low voltage circuits.

This is beneficial because it can provide manufacturers with significant cost savings as they only need to produce one relay instead of two.

The trade-off is that this design does not work well with many circuits that contain both high and low voltage components.

Remote relays

Distance relays are a unique type of relay capable of transmitting signals from one point to another. The distance between two points is the only limitation for these types of signals, making it ideal for use over long distances.

A particular advantage of this type of relay is that it does not require a power supply and can therefore be used in remote areas. This makes it a practical option for many commercial and industrial applications.

Automotive relays

Automotive relays are most commonly used in automobiles to turn certain parts of the engine on or off, which are controlled by an internal computer. This type of relay is most effective at protecting circuits from power surges because it does not require additional power to operate.

The disadvantage is that automotive relays are designed with specific needs in mind and cannot be used for low or high voltage applications.

Frequency relay

Frequency relays are unique because they use a device known as a quartz crystal.

When voltage is applied to the circuit, the crystal will vibrate at the same frequency as the input. This allows precise and fast switching between two different voltages, which can be very advantageous for some applications.

These types of relays are relatively new on the market and are not yet widely used in large scale industry, so it is important to research them before making a purchasing decision.

Polarized Relays

Polarized relays are a unique type of relay capable of controlling both AC and DC. In the design, the changeover contacts are divided into two sections, which can be used independently of each other to make the circuit work with DC electricity.

This type of relay works well because it only deals with one type of voltage, but may not be as practical as other types for use in certain circuits.

Rotary relays

A rotary relay is a type of relay that is designed to use AC but can also work with DC. To do this, it is necessary to connect the individual contacts on the contactor.

This is advantageous because it only has to deal with one type of voltage, which helps simplify the process of using it for certain applications.

Sequence relay

A sequence relay is a type of relay that can take multiple inputs and sequence them in the order they were placed in the circuit.

This design is advantageous in industrial applications because it does not require an external power supply. It can also be organized in various combinations, which means there is usually one available for each application.

The disadvantage is that these types of relays are not well suited for high or low voltage applications as they only have one set of contacts, limiting their usefulness.

Moving coil relay

A moving coil relay is a type of relay that can switch between two different voltage levels, and they do it very quickly.

This relay is often used because the circuit requires only one set of contacts to switch to operate.

Buchholz relay

The Buchholz relay is an electrical switching device that supports alternating current. It works by interrupting the current in one coil when the voltage in the other coil reaches a certain level.

All relays are enclosed in a sealed housing to protect against corrosion and dust particles.

Safety relay

A safety relay is a type of relay that is designed to interrupt current when a certain level is reached. One of the benefits of using safety relays is that they are very efficient in terms of power consumption. 

Control relay

A relay supervisor is a relay designed to supervise other relays in a circuit. They are often used when a circuit consists of many different types of relays for industrial or commercial applications.

The advantage of having this type of relay is that it prevents communication errors with different types of relays in the circuit.

This type of relay can also help control communication between different devices, making it easier for industrial and commercial use.

One disadvantage is that they use more power than typical industrial or commercial grade circuits because these types of relays tend to be more complex.

Earth fault relay

Ground fault relays work to detect voltage differences between two different parts of a circuit.

One method they use to do this is to check if the current at one point in the circuit exceeds what is expected for that part of the circuit. If this is the case, a ground fault may occur which will cut off the power to prevent electric shock.

The disadvantage of this type of relay is that they are only able to detect earth faults in a single-phase or two-phase system and cannot detect them in a three-phase system.

It also relies on the ability to measure electricity rather than current, which can lead to some of its shortcomings of not being able to detect three-phase faults.

How to control the relay?

There are several ways to control a relay. One is to use a control switch, which is usually a toggle switch or rocker switch. Another way to control a relay is to use contact control, which uses either a normally open or normally closed switch to control the relay. Finally, you can use switch control, which uses an electronic switch device to control the relay.

History of the relay

Joseph Henry was the inventor of the electrical relay. The first relay he created in 1835 consisted of a swivel metal tip and a metal plate. The wire from the coil contacts the metal tip, causing an electrical charge to be transferred to the metal plate. The metal plate could then complete the circuit, providing power to other wires that were connected to it. This relay was very simple because it gave only one impulse to start other devices.

Joseph Henry created his first electrical relay in 1835 and then improved the design by applying it to telegraphy. Along with creating this relay, Henry also used his invention for experimental purposes, such as lighting one of his houses with his newly created telegraph system. Henry also made the relay concept widely known to many people so that they could expand on it and create their own versions of the device.

Henry's invention was so important because without electrical relays, modern life would be very different. They are widely used in computers, both in software and hardware, and in other electronic devices such as televisions and automatic garage door openers. Henry's mechanism was also used to create many types of relays, such as magnetic (used in telephone systems), mechanical (used for alarms), and water level indicators.

Joseph Henry played a very important role in the creation of electrical relays, he created the first relay and also helped many people to invent new types of these devices. Without Joseph Henry, modern life would be different as we know it now, causing major problems for everything from computers to alarm systems. In conclusion, this man was an important figure in the history of technology, who not only revolutionized the relay, but also helped other people to improve this device.

Joseph Henry is credited with inventing the electrical relay in 1835. However, according to Bryant's Electricity and Magnetism, it was Joseph Henry's assistant who came up with the idea of ​​using a vibrating wire as an electrical switch. The assistant was Leonard Gale, who was working with Henry on the idea of ​​using relays in telegraphy. However, just a year later, Joseph Henry created an electromagnetic device that could actually be used in telegraphy and was more efficient than what Gale had come up with.

Henry's invention of the electrical relay was very important because it allowed power to be transmitted over long distances. Before the device was created, telegraph systems were limited by the power they could use, which caused problems in transmitting information due to the amount of power needed. By having a device that allowed power to be transmitted over large areas, the telegraph system was able to improve significantly, allowing for more sophisticated communications. In addition, the Henry relay also enabled the use of telephone systems and home alarm systems, which made it all the more important due to its widespread use in many different areas.

Video tutorial about what a relay is

What is a relay - Electronics Tutorial For Beginners