What is Relay? - Working, Applications & Types

What is Relay? - Working, Applications & Types

Summary

Have you ever wondered what a relay switch is, and why it's used in technology? It can play an essential role in controlling circuits within many different types of applications. In this blog post, we'll explain what a relay switch is and its working principle – as well as its various types – so that you have all the details needed to determine whether it fits your specific needs

Introduction

Relays are an important part of the electrical system. They serve as switches that transfer signals to other devices, allowing for remote control or automated operations in a wide range of applications. Relays work by reacting to changes in voltage and current levels on their input terminals, which then trigger them to open or close contacts between two circuits. This helps speed up process times while increasing accuracy and safety within many systems such as traffic lights, manufacturing machines, robotics arms etc.

Different types relays offered include time delay relays, solid-state relay (SSR), latching relay and reed switch matrix circuitry among others - each serving different requirements according to industrial needs across various sectors ranging from automation industry through medical equipment manufacture all the way even spacecrafts. Electronic engineers have been using this technology comfortably over decades now with ever growing advancement towards more environment friendly solutions including wireless ones! Now let's learn about what is relay in electrical.

What is a relay?

A relay is an electromagnetic switch or device which can be used to control electrical circuits. It works by opening and closing power supply lines in order to optimize the flow of current within a circuit. Along with controlling applications, it has other benefits such as providing protection from overcurrents due to short circuits, helping direct energy more efficiently throughout systems, and allowing for remote operation through automation processes.

For example, At a busy airport, relay switches control conveyor belts, ensuring luggage moves efficiently. When a cart triggers a sensor, it sends a signal to a relay, which activates the belt's motor. This sequence repeats, Similar to relay racers passing batons, it smoothly transfers luggage from one point to another. 

Relays come in various types depending on application needs; some of the most common ones are general-purpose relays, latching relays, thermal overload relays and solid staterelay (SSR). As experienced professionals have known for years now - when integrated into existing machinery or electronic equipment designs properly – there’s no limit what these powerful components can do!

Relays are an important part of the electrical system. They serve as switches that transfer signals to other devices, allowing for remote control or automated operations in a wide range of applications. Relays work by reacting to changes in voltage and current levels on their input terminals, which then trigger them to open or close contacts between two circuits. This helps speed up process times while increasing accuracy and safety within many systems such as traffic lights, manufacturing machines, robotics arms etc.

Different types relays offered include time delay relays, solid-state relay (SSR), latching relay and reed switch matrix circuitry among others - each serving different requirements according to industrial needs across various sectors ranging from automation industry through medical equipment manufacture all the way even spacecrafts. Electronic engineers have been using this technology comfortably over decades now with ever growing advancement towards more environment friendly solutions including wireless ones!

How does a relay work?

A relay is an electrical device which helps to complete the circuit and thus controls a large amount of electricity with low power. It operates on simple principles: when current passes through it, its magnet coil gets energized generating magnetic field which moves armature within the enclosed space that can be operated manually or automatically by applying voltage across two contacts points - normally closed (NC) & normally open (NO).

The switching operation on the other side of the device is controlled by the signal received from one side of the device. A relay is a switch that electromechanically controls (opens and closes) circuits. This device's primary function is to establish or break contact with the help of a signal without the need for human intervention to turn it ON or OFF. It is mostly utilised to employ a low-power signal to operate a high-powered circuit. Typically, a DC signal is utilised to operate a circuit that is powered by high voltage, such as when using microcontrollers to operate AC home appliances.

 

Construction:

 

construction of relay

Fig.1- Working of Relay

 

  1. The relay is physically and electrically driven. It consists of electromagnetic fields and contact sets that carry out the switching function. Relay construction is primarily divided into four groups. They are the housing, terminations, electromechanical design, bearings, contacts, and terminations.
  2. The most crucial essential component of the relay that influences dependability is the contacts. Good contacts have minimal contact resistance and little wear. The type of current to be interrupted, its size, frequency, and voltage of operation are only a few of the variables that affect the contact material choice.
  3. The design of the magnetic circuit and the mechanical attachment of the core, yoke, and armature are also parts of the electromechanical design. For the circuit to be more effective, the magnetic path's reluctance is kept to a minimum. The coil current and voltage are typically limited to 5A and 220V for electromagnets composed of soft iron.

 

Working Principle:

Relays are devices that use a low-power electrical signal to control and switch on or off the flow of electricity in an electric circuit. They act as intermediaries between two points, increasing convenience by allowing for greater efficiency with less cost than manually operating appliances at distance. The working of relay module principle is simple—when an electric current passes through a wire winding within the relay’s coil it creates magnetic flux which pulls down its armature and closes contacts connected mechanically to a second set of terminals functioning as output switches from one location to another.

This process continues until either power is cut off (opening circuits) or when manual button pressed internally reverts back resetting operation (closes circuits). Relay also helps prevent overloads on main device/equipment being used thus making them highly reliable form automation solutions for many applications across industries such as manufacturing, automotive engineering, construction sites etc where there needs no direct human intervention along distances involved.

The above fig. 1.  depicts the relay's interior part. It has an iron core around which a control coil has been coiled. Through the connections of the load and the control switch, the coil receives power. The magnetic field that surrounds the coil is created as current travels through it.

The working of relay module is based on the principle of electromagnetism. The electromagnetic field that creates the temporary magnetic field is energised when the relay's circuit detects the fault current. This magnetic field moves the relay armature to open or close connections. The high-power relay has two contacts for opening the switch, compared to the small-power relay's single contact. The lower arm of the magnet is drawn to the upper arm by the magnetic field. Therefore, complete the circuit, causing current to flow through the load. When contact is already closed, it moves in the opposite direction to open the contacts.

 

Relay Contact Types

It can be classified, depending on the poles and throws

  1. Single Pole Single Throw (SPST)
  2. Single Pole Double Throw (SPDT)
  3. Double Pole Single Throw (DPST)
  4. Double Pole Double Throw (DPDT)

 

Single Pole Single Throw (SPST):

 

Circuit diagram of SPST

 

Fig. 2. Circuit diagram of SPST

 

A switch with only one input and one output is referred to as a Single Pole Single Throw (SPST) switch. This indicates that it has a single output terminal and a single input terminal. An SPST switch functions as an on/off switch in a circuit. The circuit is turned on when the switch is closed. The circuit is shut off when the switch is open.

Check out 5V Relay Module

Single Pole Double Throw (SPDT):

Single Pole Double Throw

 

Fig. 3. Circuit diagram of SPDT

 

A switch with only one input and the possibility to connect to the switch between two outputs is known as a Single Pole Double Throw (SPDT) switch. This indicates that it has two output terminals and one input terminal. A circuit can use a single pole double throw switch for a number of purposes. Depending on how the circuit is wired, it can act as an on/off switch. Or it can connect circuits to any two different paths that a circuit may need to follow in order to function. For instance, a printer's Ready Mode and Standby Mode can be created by connecting an SPDT switch.

Check out 12V Relay Module

Double Pole Single Throw (DPST)

Circuit diagram of DPST

 

Fig. 4. Circuit diagram of DPST

 

A double pole single throw (DPST) switch is used to link two source terminals to the corresponding output terminals. It contains four terminals (but never to each other). In an "ON/OFF" configuration, a DPST switch can be utilised with its terminal pairs either connected ("ON") or disconnected ("OFF").

Double Pole Double Throw (DPDT):

Double Pole Double Throw

 

Fig. 5. Circuit diagram of DPDT

 

A Double Pole Double Throw (DPDT) switch is a switch with two inputs and four outputs, each of which can be connected to one of the two corresponding outputs. A double pole, the double switch has two possible orientations for each of its terminals. Due to its versatility, the double pole, double throw switch. It may be connected to 4 distinct outputs with just 2 inputs. A circuit can be rerouted into one of two operating modes.

Check out Solid State Relays

 

Types of relays:

Relays are an essential equipment for countless applications in the power system. They come in a variety of types and can be used to perform various functions related to protection, safety, control or automation. Depending on what they’re being used for, relays may take different form factors such as electromechanical relays (EMR), static transfer switch (STS) or solid-state relay (SSR). EMRs use current flow through coils that generate magnetic fields which actuate contact mechanisms to open/close circuits when specific conditions occur. STS is typically used for switching loads between two sources while ensuring uninterrupted supply with minimal downtime whereas SSRs rely on semiconductor devices like transistors and transducers without using moving parts making them reliable but more expensive compared other types of relays.

Relays can be divided into several types based on their features, architecture and uses, etc. Here, we've included a few of the more typical relay kinds.

  1. Electromagnetic
  2. Latching
  3. Electronic
  4. Non-Latching
  5. Reed
  6. High-Voltage
  7. Small Signal
  8. Time Delay
  9. Multi-Dimensional
  10. Thermal
  11. Differential
  12. Distance
  13. Automotive
  14. Frequency
  15. Polarized
  16. Rotary
  17. Sequence
  18. Moving Coil
  19. Buchholz
  20. Safety
  21. Supervision
  22. Ground Fault

 

Applications of Relay:

When galvanic isolation is desired, relays are employed whenever it is necessary to control a high-power or high-voltage circuit with a low-power circuit. Relays were first used on long telegraph lines, where a contact may be controlled by a weak signal received at an intermediate station, renewing the signal for further transmission. Small, low-voltage wire and pilot switches can be used to control high-voltage or high-current equipment. Followings are the major 8 applications of relay.

  1. Lighting control systems
  2. Industrial process controllers
  3. Traffic control
  4. Motor drives control
  5. Protection systems of electrical power system
  6. Computer interfaces
  7. Automotive
  8. Home appliances

Conclusion:

In this blog, we understand what is a relay, working of relay module, relay contact types and different types of relays and applications of relay. We have seen relay works on the principle of electromagnetic attraction when it gets energized it operates according to the signal given. Nowadays, this signal is given by the micro-controllers or microprocessors. These relays are also used in power system operations to detect and prevent the fault.

 

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Frequently Asked Questions

1. What is a relay used for?

An electrically operated switch that's utilized for the regulation of electrical current flow in a circuit is a Relay. It operates by either opening or closing the circuit based on an electrical signal, granting it the power to manipulate the flow of electricity to various electrical apparatus such as motors, lights and other electrical components. Relays have become a ubiquitous presence in automotive, industrial, and communication applications as they grant control over high-power devices using low-power signals. Moreover, they provide insulation and protection to delicate electronic devices by keeping them isolated from high voltage and current sources.

2. What is the principle of relay?

Relays essentially function as a switch that operates to control the flow of electrical current in a high-power circuit with a low-power circuit. It operates by harnessing the power of an electromagnet, which, when activated by an electrical signal from the low-power circuit, opens or closes the switch like a whimsical puppet master, controlling the flow of electrical energy remotely. Used in a plethora of applications, relays are ubiquitous in control systems, protection circuits and electrical distribution systems, serving as the gatekeepers, safeguarding and isolating electrical loads.

3. What is difference between relay and switch?

Relays and switches are two electric components that regulate the flow of electricity in a circuit, but they differ in their mode of operation! A relay is an electrically operated switch that harnesses the power of an electromagnet to either open or close a circuit, while a switch is a mechanical device that opens or closes a circuit physically. Switches can be activated manually, but relays are typically controlled by electrical signals. When it comes to usage, switches are utilized in applications that require low power, whereas relays are employed in high power applications where manual activation is neither feasible nor practical.

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